Dueling is legal in the city. It is regulated, though. Both participants must be evenly armed and armored. Magic weapons and armor are legal, as long as both duelists have roughly equal items. No other magic is allowed. They must have a second. A person of standing must attend as the judge, whether that is the local innkeeper or a knight.
Commoners may not challenge nobles. Nobles of lesser rank may not challenge nobles of higher rank without good cause.
Duels can be to first blood, first serious wound, or even death. In all cases, the judge present must acknowledge the result of the duel.
Cheating is heavily frowned upon and the opponent is allowed one free strike if a cheater is discovered. If someone cheats using magic in a normal duel, he is immediately executed.
Magic duels also occur but must be held either in a protected, enclosed space or outside the city where nothing can be damaged. In these cases, a wizard or cleric of note must preside as judge. Both participants must be able to use magic for the duel to be legal.
A champion may stand in for a duelist if the duelist is unable to fight or the challenge is for a frivolous matter. Powerful nobles also have standing champions to defend themselves in duel and generally don't engage in dueling. The issuer of the challenge to a duel must fight, he is not allowed to use a challenger.
Frivolous or frequent dueling will lead the the banishment of the duelist. While the Count doesn't mind matters being settled martially, he doesn't want people making a habit of it.