Posting just to show love for Blue Exorcist, even if its a stomp.
Rin's strength is weaker not greatly far off Nero's human side, who also takes durability. Regen is at or above DT-Nero and while the blue flames may not burn him, Rin can still fire off low-building level damage with them.
Speed equalizes (dodged a bullet?) and with Nero unable to use Yamato or his Devil Bringer, this would be more of a fair fight.
well, the manga is only at chapter 46 or so due to the author's updating schedule and right now, it's pretty lax for the characters who are just dealing with their own things until the next big arc. that said, I do recall at one point it being said that Rin's powers are a lot like Satan's himself, who is naturally the strongest demon in the series. it indirectly states that he will one day be able to possibly achieve the same level of power as him and given how casually Mephisto does all of the things he does in the manga thus far (like transforming, making his own little pocket dimension, though I could be wrong on this part, amongst other things like casually holding Rin in his berserker state) that is saying a lot.