In Skyrim.. enemies should do the same damage and have the same health but simply be more skilled with their chosen weapon.
ie if you are fighting a bowman on 100% difficulty, make them quick shooters and excellent shots.
for a swordsman.. make them swing fast and hard, block better, and enable them to roll side to side like the player can once his acrobatics is high enough.
Same if you play on easy, just make bandits terrible, slow and sloppy fighters.
It would be a better system than the static oblivion method.