Next time you feel bad because you don’t fit into some social beauty standard, please remember that dueling scars used to be de rigueur among Junkers and other landed nobility of Prussia, Germany, etc. They were a signifier, a way to let people of your upper class know that you were like them (because you were the type of person who a) could afford to have hobbies and b) had hobbies like fencing), and as a way to show how badass you were (sure, you may have lost the duel, but you can take a blow, which is just as important).
As with most trends, people outside the originating group began to emulate the behavior, and scarred themselves with razors. With a simple cut, it’s easy for everything to heal nicely enough, so some dudes would put horsehair (an irritant) into the wounds, so it would scar up nice and big.
Outside of the social signifier aspects, when the Third Reich was born, it also helped you to look like you came straight from Central Casting, like SS-Obersturmbannführer Otto Skorzeny here.