User blog comment:ImperiexSeed/The oldest being, archangel or leviathan?/@comment-98.113.182.208-20120514020316/@comment-4920092-20120514143729

Well, Cas wasn't even an angel at that point - the angel blade didn't work on him, and Death called him "mutated," so it's possible the power-stopping trick wouldn't even phase Godstiel.