User blog comment:Gilgamesh79/Demonic Energy and Magical Energy/@comment-82.178.102.63-20170829160229/@comment-1359322-20170910022951

@Tengen, from n0m@n's post in animesuki:

"Anyhow, for Ise's current strength, people refers to him and Bina (Grayfia) as above Maou-class. Ise still has a incomplete DxD in this volume so I guess he's still not in a God-class zone yet because of it. In this series, when people refers to Maou-class powers they are using the original(previous) generations of Maou and the current 4 Maous are all above that power-level so its not surprising Grayfia is above Maou-class too (since it was mentioned she was like Serafall's rival where they once fought each other for Leviathan's position)."

So the correct term would be God-class > Original Maou-class. Since the Maou-class set by Serafall & Falbium may already be in the level of God-class.