The Gloves by their description upon a hit make successful hits up to 20% less likely, plus basically decreases your spell and other resistances by just as much.
If you ignored the cirticals for a moment, It could be akin to changing your hit and miss patterns from
this one to one more similar to
this one(and that's but on the attacking end).
Translated to Pillars Of Eternity Deadfire for anybody who's played that's similar to an up to -20 penalty on accuracy (the primary to-hit stat that risese by a measly +3 per level) plus gaining up to a -20 on almost all primary defenses.
There's RNG for sure (that's D&D and similar systems) and then there's begging the gods of probability to show some added mercy. Don't have to like that, naturally.
Well, at least it's only on the character wearing it.
Or isn't it?