Is Rias Gremory Weak?

Intelligence: Rias is considerably skilled in using magic and demonic energy, and is regarded to be so talented that she can reach the highest grade of devils without any sort of training.

How strong is Rias Gremory?

Azazel noted that even without training, Rias has the potential to become one of the highest class devils using natural talent. She was capable of overpowering Ultimate-Class Devils wounded by Crom Cruach, while in her Balor Princess Form, could keep up with Fenrir at 80% percent power.

What rank is Rias Gremory?

In the English dub of season 2 of the anime, Rias says her family's rank is Marquis even though it is actually Duke. In the light novel and manga, the Gremory's live in a castle but in the anime, they live in a mansion.