User blog comment:B214/Volume 23 discussion blog/@comment-73.46.6.122-20170318162505/@comment-10330822-20170319014305

Well, out of ignorance of what Bova and Nakiri can actually do, I feel we can really say. 1, I feel Grayfia isn't able to fight as she usually can because she's undercover. 2, Issei had trampled the Satan-Class Devil Euclid Lucifuge, and he was supposed to be every bit as strong as his sister, back in Volume 17, and he couldn't even touch Vasco in Volume 19, and Vasco was fighting multiple people in addition to Issei.

So yes, I feel Vasco could take Grayfia on by himself, and I believe he is Satan-Class. Whats more, Asia and Ravel themselves aren't that dangerous, except maybe for Asia using Fafnir. But still, remember how many people Vasco took on in addition to Issei, that's why I'm saying "minus Issei". Grayfia might bridge that gap, but I don't know, if they had Roygun I feel they'd have a better chance.

Its just, as things sit, Rias's team as both Crom Cruach and Vasco, both of which Issei has never been able to beat. Sure, Issei could probably beat Vasco with DxD now, but still, that's a testament to that groups strength.