[It's entirely possible he's found plenty of sore spots in the past -- but Mephisto was able to lie his way out of them. Regardless-- he won't respond to that little comment about him being harder to kill now, but it does manage to bring the smile back to his face.]

Oh no, there's one other weakness I posses. And while not on par with my heart, it is considered a demon's most vulnerable point.

And that point would be my tail.