I gave up and came back to it a number of times, but finally I beat him with Scorpion. I went into Konquest one last time with a score to settle with that son of a bitch, and after an incredible amount of swearing and yelling, I beat him.
Basically, you've got to play as someone whom you can really tear it up with without so much as stopping for a breath. You've just got to attack constantly, and to be honest, it's more luck than technique. If the fighter you're using doesn't have a decent style-branch combo, though, you can pretty much forget about it.