] Duels were illegal in those times, and in order to fight the participants would have had to go to a quiet location, probably out of town. They certainly would not have been facing each other down in a public square, or anything of the kind. The fact that no one knew anything about this shows what kind of secrecy they would have had to maintain about it.

There's a lot of material on L&T about duels: here's a link to one post. This indicates that it wasn't very easy to kill or maim your opponent in a duel: there's no need to suppose that either Brandon or Willoughby missed deliberately.