Robots could totally have passive abilities, like battery recharge, constant electrical shocks to enemies. I'd be fine with mice phobias and bug phobias where they're too scared to fight the creatures.
I'd hate a negative accuracy all the time or I'd just use spells that have a high accuracy rate. BUT having his HP less than 25% and his accuracy drops. I'd be fine with that. Makes sense, if you're in a hospital bed dying how accurate would you be?
Or the longer he is away from an inn the more his magic drains? He could just have a weakness to poison or elemental magic.