Deamon Arch Wings found in the cave of darkness

[sagk]

I have taken Seimon in and he dies when he opens the chest. I have tried different people with him different weapons and any thing else i could think of is there a secreat to opening this chest? I would love to get the wings.

[Tilly Mint]

I never managed it but Seiman was under L50. I assume he needs to be higher.
I've finished the game so I don't think they're essential.