Or maybe Lamm had the dagger for the same reason he had all the other loot - he nicked it.

Re loot
I've written Cassian's family as being poor by the standards of nobility but they still have a townhouse in North Point. That should be a safe location to stash our loot until it can be sold off.

According to the core rulebook, religious symbols are common items, usually made of wood, and worth 1 gc (table 5-11 Miscellanea). The abalone shell might be worth a bit more since Lamm decided to hang onto it.

An armoire seems like a stretch when looking for an equivalent to a cigar case. An armoire is significantly bigger, so the wood alone would be worth more. A small wooden chest (2 gc in Old World Armoury) or a tube case (1 gc) are probably closer in size.

The rest of the stuff is clearly art or jewellery in some form. Prices for jewellery can be found in Old World Armoury but I've no clue where to find the value of art objects specifically.