I think this would add a lot to Adventure mode; here's my ideas on how it would work, basically.
You steal something or hurt someone, and a big person of authority comes up and challenges you to a duel. Being the one challenged, on the chat screen you are allowed to choose your weapon. Basic responses could be;
"Hah! You should know that I am the greatest swordsman who evel lived! Prepare to be smitten!"
"I see. A fine weapon, although, not of my choice."
"Oh. I am not skilled at that weapon."
(with this one, it can branch; if he's excitable and adventurous, he'll take you on anyway)
"Prepare to die, nonetheless!"
(or, if he's less tough+mean:)
"I am not fit to challenge you."
So in the chat screen, you have a new option;
"Duel"
And then a confirmation box;
"Do you really challenge [NAME] to a duel?"
If he's a tough big guy who's skilled and you are a big tough guy who is skilled, you'll get;
"I accept your offer. Therefore I choose the weapons." So it's wise to duel with somebody who uses the same weapon as your highest skill.
If he's tough and you aren't:
"Stop wasting my time, weakling!"
If you're tough and he isn't:
"I decline."
If you're both weak:
"Fine! I'll fight you!" (lack of weapon choosing; you both use whatever is in your hands, or just hand-to-hand combat)
Legends could then record injuries (foot smashed etc) in the same style as the duels of worldgen. =D