Regarding an affix not doing anything?

I wrote in “discussions” on steam but it kinda got buried so I’ll just copy paste it:

Confused about an affix on weapons.

I have a weapon and it has a stat saying “Stamina increased by x%” (23% in this case). So on the stat sheet it doesn’t increase stamina while equipped (other stats like resistances do), I have 60+ stamina so it should be a visible increase. I then checked if it just doesn’t register on the sheet by comparing rolls with and without it equipped (still staying in the same weight class). The rolls uses the exact amount of energy per roll so it isn’t a stat increase.

Then i thought maybe it has to do with the weapon getting increased stamina cost, but it’s a unique weapon without a red stat so it shouldn’t be a negative stat. Ithought to test this even though “Attack Stamina Cost inc/dec by x%” already exists. It also has the same stamina cost as other greatswords so it’s not that. Also tried to compare the usage while swinging, because maybe (as I said before) it counts while doing the action (with the specific weapon) and not on the sheet but it uses the exact same amount of stamina per swing as any greatsword.

I might be dumb and am just missing something or is it bugged or maybe just badly worded? If it happens to be a bug, maybe there’s more stats like that one?