Hmm... If we weren't capped at Level 4, I might suggest a Remove Curse spell. But I'd think that killing the character, removing the cursed item, and reviving them should still work. I'm not sure I can think of a mechanic that justifies a permanent effect in this way.
Even requiring the death of the character seems a little extreme: the original wearers of the masks got periodic saving throws against their effects.
I mean, on a practical level, I'd say that this is why we "Save early, save often" - and that goes double for a game that's still under development - but I do think that you've identified something that probably ought to be changed.
