Is defeating enemy with your fist the only requirement to get +1 fist?
If so then I think the spell with rune that increase max cap of health by 2 and heal by 1 or increase max cap of hunger by and fill 2 hunger depend on what you use it on might be bugged when use on fist. It increase fist cap by but when I kill enemy with 3/4 fist I can't get another fist card to drop
Edit: Nevermind, I figure out what's the reason for this.