My gut is telling me Yuuto, but it has been a while since I've seen both series.
Yay Sonata's back, Taka did a really good job handling things in your absence. But real life issues come first so don't push yourself.
I leaning towards Yuto here. Yuto could take him with a Holy Demonic Sword which would indeed burn Sebastian's fingers off if he touched it unlike his battle with Claude.
@LHWKnight: Yeah, i don't spend as much time as i used to on here. But i'll be more active in dxd invovled battles. So i'm on summer break before next week is over.
Also, have you considered joining the rpg verse. I really need a good partner,
Edit; you know you're more than partner, a friend.