I'm a little underwhelmed how any effect which causes the loss of Stress or Fatigue is simply converted to Wounds against an NPC. Has anyone toyed with an idea like this:
Each point of Fatigue "damage" against an NPC reduces its Aggression. If Aggression is 0, then cause wounds. Stress works the same way, but against Cunning.
I know lots of monsters don't have a ton of A/C/E, but this at least seems to give Stress and Fatigue damage a slightly different effect in-game than merely converting it to Wounds.
Does anyone see any major drawbacks to this sort of house rule? I haven't tested in play yet, but I'm considering it.