Imperius can’t be Wrath cos there’s already one; the Sin General Wrath. I think Imperius can be the Aspect of Conquest (Pestilence) which can start a Four Horsemen storyline. They can say that Imperius was fueled by rage over his defeat in the High Heavens, coupled with a bit of jealousy on the Prime Evil after almost invading Heaven, which is quite a feat given that they are always locked in eternal stalemate where neither is gaining the upper hand against the other.
PS. Deckard Cain should be the Angel of Justice. Being a human, Cain witnessed and experienced the good and bad side of humanity, which makes him somewhat unbiased and fair.