"Monsieur Crownguard! Comment allez-vous cette belle journée?"
"Voulez vous coucher*avec la mort?" (Would you like to sleep with death?)
*coucher is not necessary but can be added to emphasize the point
I'd say lots of cafes, coffee drinking scenes, you need prim and proper manners and you will have to do some stereotypical insults. You have to look these insults up, voulez-vous is a very polite way of asking someone to sleep with them, but you can play with the words like I did and make it imply would they essentially like to have intercourse with death.
Here's an example scenario, she's sitting at a cafe with coffee and a pastry, musing about the pretty things in life, someone comes challenges her but she refuses."Incroyable! (Incredible!) The finest swordswoman in all of Decamia refuses a duel? Pah! Vous êtes un cochon et un fou! (You are a pig and a fool!)"
Her response, "Incroyable, un cochon et un fou speaks to me (Incredible, a pig and a fool speaks to me). L'etrange things in life. (the strange)"
"You dare?! Have at vous!"
I find if you combine French words with English it helps add on to the absurdity and make things sound sophisticated and somewhat funny at the same time by intermixing the two languages. What I mean is, with the more creative insults you can use French so it sounds dignified, then use English for the simple things to create the divide between sophistication and layman terms.
Just for future reference, I'm reaaaaaally reaching with the French, my French is quite rusty, this is pushing my limits.