In fairness, Dawnfang/Duskfang (The swords from oblivion, and what got me through most of the game) would do fire/ice damage respectively, which are two effects in game already. so why not go with that?
+1 because oblivion and elder scrolls is love. I'd say the animation for the light should be like a flashbang and the darkening effect should be like a black cloudy mist.