Uhhh.... yeah? Because he tried to rape me, and instead of utterly destroying him, we used him as a political tool?
What; she's pissed because he "aint'nt DeD?" Or she has a weird way of saying thank you, maybe?
Sheeeeeesh...
I bet this duel either takes 3 chapters, or just part of one, but either way... im guessing we get the old "says something in MC's ear with a dark expression of evil, and shakes hands, calling it a draw and being all nice about it."
I've only seen it in every manga ever written, but it's still just a guess...