While writing new entry of my campaign report, I again remembered a case where a player used fate point to turn an unarmed sneak attack strike in to a mighty blow. My question is - what should happen with an unarmed mighty blow? The rules don't answer that. Normal weapons break. I didn't want the combat to freeze for a such petty thing, so I just threw some dice of damage to the character as a result of striking so hard unarmed.