User blog comment:Crimson and Darkness/Volume 24 discussion blog/@comment-33939194-20171219002346/@comment-24595619-20171219031444

Azazel mentioned that he was as strong as an Ultimate-Class Devil. Using it he defeated Shalba and Barakiel, so he's at Satan-Class. But, it's mentioned that Issei can't draw out its full potential since it requires him to master Illegal Move Triana first.