Problematic wounds
A problematic wound is one with lasting fictional consequences. Characters suffer them when you hurt them or make another GM move that involves a character getting hurt in a specific, consequential way. Simply describe the wound in the fiction. It's now true! A twisted ankle can't bear weight. A blow to the head leaves them staggering and dizzy. A severed hand is severed, and they're probably bleeding out (and in shock). These sorts of problematic wounds should be particularly common when messy attacks are involved.
Problematic wounds often involve PCs marking debilities and always involve taking damage (i.e. losing HP). If an NPC breaks a PC's fingers, the PC can't make a fist, is probably weakened or dazed or miserable from the pain, and is going to take 1d8 damage (ignores armor). The damage won't kill them if they drop to 0 HP, but it could take them out of the action.