Aiyeku:
Aiyeku, the Collect of Treasures, Second Circle soul of Ensara, and a girl basically looking like this combination of thief, scavenger and demon carrying a big bag, sees Edward going for the space marine armor of Zhargeon and says
"Oh you want this one, Edward? Okay."
And clean of it chaos corruption with some green fire, her eyes temporarily looking like Ensara's for a moment and leave it to him to pick it up, seemingly no less damaged than before but now clean of chaos. Aiyeku then goes off to scavenge some space marine armor elsewhere, seemingly picking up tech and putting it in her bottomless bag.

Second Meeting with Eldrad:
Sooner or later, the scavenging will end, and the leaders of the Sabre will meet with Eldrad on screen again. While some things are easily settled...
"Kaerabryn has been saved, farseer."
"Good. That was all I wanted."
"Also I've managed to acquire a quite a bit of spirit stones which I'd love to give to you if you let me on your ship."
"Indeed, we'd very much appreciate them, and due to our....population issues have a bit of a surplus of Eldar technology we can exchange for them."
"Sounds like a deal"

Other things however are a bit harder:
"Eldrad Ulthran" says Rhiannon "We found this Forge of Vaul on the planet, and I think it'd be appropriate to give it back to your people."
"Nonsense, Rogue Trader Rhiannon, keep it, consider it a gift from the old Eldari Empire, we don't need it"
"No, I insist, the Forge of Vaul should be back with its people."
"No no, I insist the humans should have it, let them have a chance at wielding it."
This continues back and forth a bit, neither of the two seemingly willing to keep the powerful warp-based nanofabricator. Ensara asks
"Okay, why are you two trying to pawn the Forge off one each other? Don't you guys hate each other?"
"Yes" says Rhiannon "But I'm also wise to what would happen if the Imperium tried to use such a device. Best case scenario, it gets thrown into some Inquisition vault to be studied by tech priests allowed to see it and nothing comes of it. Worst case scenario, its actually used to try and gain a victory against some other enemy in desperation and ends up only causing a more horrible loss by dragging the entire planet its on into the warp, thus making a new Daemon World. So I'm trying to get rid of it so the Eldar use it instead"
"Meanwhile I know what the Old Eldar Empire was like. Not doing that again. In Eldar hands, it would cause nothing but decadence and hastening our species into the clutches of She Who Thirsts. I am not repeating the Empire's mistakes. Therefore the humans should get it, they have the numbers to expend on it going wrong without it harming their species in a major way."
"Really!?" Kaerabryn says "Your both trying to play hot potato because you think the Forge of Vaul is a ticking time bomb waiting to make things go wrong!? Do you not see how it could help? It could make anything! It could literally change so many things for the better!"
"Something WILL go wrong from using the Forge, Kaerabryn" says Eldrad "It is like a Psyker, a glorified version of our Bone-Singers. You saw what happened down there, the more the Warp is used, the likely things go wrong, each you use it, you spin the wheel and hope you get a good number. But you get a bad one....daemon appears and we have to hope it doesn't kill too many of us before we kill it. Assuming the Forge itself doesn't get possessed, or corrupted. Probability over a long enough time, becomes inevitability. It will only lead to a repeat of our downfall."
"Farseer, you speak of decadence when talking about the Eldar, as well as it being the cause of your species downfall, what do you mean?"
"Well hm....your human so you probably don't know. I owe you some explanations anyways. Though honesty a lot of this is all tied together so I'll try to bundle it altogether in one:

To understand the Fall of the Eldar, you must first understand that the Eldar despite our superficial biological similarities to humans are fundamentally different both biologically and spiritually. Our souls shine brighter in the warp, our senses of sight, smell, hearing and touch are many times greater than a humans, our hearts beat faster, our minds process things faster than humans and our physical reactions are too fast for the human eye to follow, we experience a wider spectrum of emotion, have senses that you do not, we love far longer and so on. This isn't inherently better than humans as our advantages come at certain costs: we're more complex organisms and thus we require more effort to make, having longer gestation and development times and requiring more complex chemicals than humans do, as well as requiring more than a single session of lovemaking to make a child, unlike humans we can't accidentally have a child from a one-night fling, and even at our height we never had a population size comparable to other more faster-breeding species.

Thus as a result of all this, Eldar live at a....greater intensity than humans do. Every emotion could reach heights no human is capable of feeling. Every sensation we experience far more acutely and intensely than a human. Every quirk, passing interest or like could develop into obsession or mania with far greater ease. At the same time, every trauma, every moment of despair, or rage or pain could affect us far more intensely than a human ever would. For example, every time we lose a loved one, that is a sadness so great we cannot express in any way that you'd understand in this language, you do not have the words for emotional intensities we have, losing Kaerabryn would've been quite despairful indeed, perhaps even éadóchas mór lán for she is one of our youngest and thus the future of the Eldar. Knowing this, our ancestors sought in their technological pursuit, to maximize pleasure and our feeling of sensations and positive experiences so as to create utopia for ourselves, even immortality through the warp so we'd never truly die. Of course due to our ability to process things fast, we quickly grew bored of the usual pleasures and games and began to....get creative and excessive. We started to mix in pain with the pleasure to give the pleasure more meaning as well as get forms of pleasure from pain, and both pleasure and pain spiraled out of control, especially since we could come back from death, so we started killing each other for FUN, torturing each other for FUN, the games and recreation ever growing more elaborate and optimized to produce the greatest highs possible until.....It Happened. The Fall.

The Eldar's intense potential to feel emotions, combined with a decadence no other species in this universe could ever match due to our technological heights, over thousands of years shaped and contributed to the warp to create.....She Who Thirsts, who broke forth from it as she was born and devoured most of the Eldar along all but three of our gods, of those who survived, Isha goddess of healing and fertility was kidnapped by The Plaguefather and his captive to this day, Khaela Mensha Khaine was shattered into many shards by the Hound of War, and finally Cegorach the Laughing God who escaped and helps from the shadows to this day.

Our biology and souls are directly tied to our fall. It is unlikely that any other species could've fallen in the exact same way."
"Okay, hm, so Chaos gods can be created? They're in a sense, artificial? Not natural?"
"Indeed, even if their creation isn't intentional. Cegorach told us that Eldar once created all the Eldar gods intentionally, but that somehow we lost the ability. The chaos gods existence is like pollution, they are the result of accumulated psychic waste and run off from the Materium. The Warp used to be a lot calmer, a lot more easy to use, less dangerous. But....things happened that changed that. She Who Thirsts is only the final stick the broke the camels back as it were, as these changes didn't happen all at once, but rather were the result of events long before humanity ever could do anything about this. Before humanity even got out of caves, the ancient Eldar, the Old Ones and the Necrontyr and the C'tan fought in the War In Heaven, an ancient conflict sixty million years ago said to be far greater and more terrible the conflicts occurring today. The details of this war, have been lost to time but is from this conflict we speculate that the other three Chaos Gods come from."
"your not sure?"
"It is admittedly possible that one or more of the Chaos Gods could come from a future event, technically. The Warp is timeless. Once a warp entity is born into it, it is technically outside of time for all intents and purposes. Linear time is a thing of the Materium, and the Warp does not follow that rule- it can't in order for Warp travel to work."
"But doesn't that mean that the Chaos Gods could simply stop us along any point in time? Or something like that?"
"In theory, perhaps if the Warp were calmer. In practice no. It is theorized the Warp's current turbulent and chaotic state works against them in this regard, swirling and mixing moments in time so that they occur out of order and thus the Chaos Gods from their timeless point of view can't control WHERE or WHEN they interfere with the Materium. In that sense, they are opportunists affecting whatever change they can with as little psychic energy as possible for maximum benefit to feed themselves from whatever feelings they get out of people. Like merchants that want to get the biggest profit out of the cheapest thing they can sell."
"But if the Warp calms?"
"The Warp being calm while the Chaos Gods are alive is impossible. They are the source of its turbulence, its chaos. If they were to die, the Warp would return to a calmer state and would have no affect on anyone's minds. They are not unkillable, as Khaine demonstrated such great warp entities can at least be shattered into smaller shards of themselves, and as She Who Thirsts demonstrated, they can be devoured to empower another entity at the very least. The Eldar's previous plan before meeting with you Jumpers was to make our own God of Death, Ynnead to fight She Who Thirsts to kill her and calm the Warp to some degree and thus lift the curse from our species, as speaking her name allows her to devour our souls. The Emperor hoped to starve them out, so they would go back to being relatively dormant before She Who Thirsts was added, as the Warp while not ideal wasn't nearly as bad before She Who Thirsts was born. The problem is figuring out how kill the Chaos Gods in an absolute sense- you can relatively kill them by shattering them which would take some time to gather their shards back together, as energy they could be devoured. The problem of killing them in an absolute sense so they're gone forever is that people produce the emotions and feelings that lead to these entities existing: Rage, Despair, Hope, Pleasure, are things all beings experience at some point in their lives. The Chaos Gods would not come back immediately from such emotions gathering together again, it took many life times for even us, the Eldar on a massive game to create even one of them and the new entities might not be the same ones, but they'd probably be just as bad"
"Why do you think these new entities would be just as bad?"
"Because negative emotions are stronger, or perhaps more violent in the Warp than positive ones. The warp entities you all see are negative, because if any daemon of something positive ever came into existence they'd be completely peaceful and fragile, unable to hurt a fly and saintly. Imagine a daemon of compassion trying to fight, or a daemon of patience trying to act quickly- it simply would not happen. As a result, such a being would be quickly destroyed by the negative, violent daemons that the Warp is now made of."
"What about something like a daemon of courage?"
"If the Blood God's presence is any indication? Well you can't have courage and fighting in a war to protect others, without killing, hurting and rage. Alex with her powers might be an exception to this, but she is just that: an exception. The base truth of such conflict is that you can't extricate the good from the bad. The same emotions and behaviors that give rise to noble courageous warriors are the same behaviors that give rise to murdering psychopaths, as any warrior inevitably must use their anger as strength to fight to some degree, its just natural. What separates from a cultist from a non-cultist is how much they give into it. Thus do the Chaos God feed upon the entire galaxy to sustain themselves every day. Thus will any entity that arises from the Warp will slide into being negative unless you somehow figure out how to change the Materium's people to not produce them. But to get rid of these emotions in an absolute sense would be to brainwash all the people in the galaxy- a solution I don't think is desirable or realistic."
"Your making solving this sound real difficult."
"That is because of it is. We're the foremost experts on the Warp, and we have been contemplating this problem for ten thousand years. If there was a better solution we could come up with ourselves, we'd have done so....though, there is a possibility.....that there might be a new solution somewhere in the Black Library. A solution that you Jumpers can do, that we can't."
"The Black Library, what is that?"
"A Library of Eldar creation. The greatest Library ever made. It exploits the timeless nature of the Warp to gather not emotions, but knowledge across all time and space. All knowledge that can be known in this galaxy, is there. Possibly the universe, but no Eldar has been allowed to look into it long enough to find out. From it, we got the prophecy that told the Eldar would fight in the Rhana Dandra, the final fight against Chaos, somehow defeat She Who Thirsts and ensure a better future for our species. Perhaps it can tell you a solution that no one otherwise knows. But....not just anyone can go there. It is hidden deep in the Webway our method of traveling through the galaxy, and only allowed to those who have conquered the Chaos within themselves by the Harlequins and Cegorach himself. For the followers of the Fateweaver were to find it, who knows what they'd do?"
"Hm..." Ensara says smiling "All knowledge across time and space you say? Interesting. I think we should check it out sometime."