Realky clever move there By Sharkan!

Okay, I assume the chain jiggles a bit from being attacked. Does each segment need to be attacked to break it, or is the HP for the whole object? Sorry for the IC physics question! With max power attack and damage halved for being underwater, cypher does 1d4+8 damage, so three attacks might do it.

If he knows that the chain next to him will be unweakened by whatever jiggling is going on then he'll try to disarm again if possible. If the chain looks substantially thicker than normal chain he'll also try to disarm again. If the box hasn't moved very far inside the ship hopefully the hippocampus hasn't moved much either and it'll still be possible to reach it (+/- movement).