It is actually not permissible to duel. You can engage in "friendly combat", but duelling to restore your honor is both illegal and dishonorable. (The German fraternities, which are responsible for these fights, gave their word of honor that there would be no more duels to satisfy insults to honor)

It is also an extremely stupid idea that scars are somehow an "authentic mark". As somebody who fought three of those "mensuren": Scars are a sign that you thought you are better than you actually are. It's the embodiment of "Dunning Kruger walks here".