User blog comment:EmpyreanSmoke/Supernatural Q&A/@comment-27457157-20150816070359/@comment-24834479-20150819001750

Power is more of a fluid thing is the Supernatural universe. While the Leviathan are older than Angels, have a lot of physical strength, and can kill/eat any angel, they don't have as much magical strength, which makes their power stance complicated. Could they chomp on an archangel? Sure. But it is also possible for an archangel to beat a Leviathan.