I could see Muscle being a disadvantage for mages, like, you get so strong that you snap your wand in half accidentally? That could be the counter to Green Gems, with the "don't use" case being for Warriors.
I think what the dev meant by "uncursing" was what you do with the cursed cow bra. Either that, or it's just something the NPCs say for worldbuilding, since if the character wasn't so adventurer-defeatingly-inclined, they might actually want to do that.