The potion of restore ability can be used to recover lost maximum Pw. It only restores maximum Pw, not current: if your Pw is 30/80 and you previously had 100 maximum Pw, these potions will only be able to get you to 30/100.

• If cursed: does nothing (as usual)
• If uncursed: you recover one quarter the difference between your current maximum and your peak maximum, or 5 points, whichever is greater.
• If blessed: you recover half the difference between your current maximum and your peak maximum, or 10 points, whichever is greater.