WTF does that even mean? A duel without witnesses is just a public execution? Seriously WTF? There were plenty of witnesses. Also, isn't it convenient he showed up right before she finished him off but he was mysteriously absent when that kid was about to be cut down? At this point the knight is just a watchdog for those nobles. He doesn't use violence to keep people in check, instead he uses the law to keep the nobles safe and the people oppressed.