So, in the video game FitD combat system, the default harm inflicted by a player is probably 2. That's how much harm a 4-5 result with full effect will do, all else being equal.
This is, I should add, perfect for a situation like Blades, where there should not be fair fights. Keeps Things short & brutal
Ogre
Harm: 3
Moves:
* Knock a Combatant out of the scene
* Property Damage
* Ground Smash knocks everyone back
1-3: harm 3
4-5: Monster Uses a move
6: Inflict harm on the monster
(Set aside how much harm the monster can take for now. Different problem, but not a hard one)