Originally a Dueling Scar was a scar on the face, usually on the left cheek, resulting from being cut by a sword in a duel. They're part of the stock uniform for a sinister Nazi or obsessive, pickelhaube-wearing Prussian and have become a fairly common accessory for any sinister military man regardless of origin. To qualify for this trope, the scar needs to be on the face and used to make a character look more militarized and Badass. The scar need not necessarily be from a sword or an actual duel, although writers should get extra credit if they know the origin of the trope.