Six hundred years ago unregulated sword fights were becoming more common in Europe - in both public and academic settings. If you had money (noblemen) or were learning something (students), you were surrounded by violence. It was so widespread that wearing a fucking sword was like wearing shoes or a hat. It was part of how you got dressed.
Seems kind of ironic that they would get all dressed up only to hack each other to pieces.
Over time, structure was introduced and regulated dueling became an option for students and nobleman. That meant you had to schedule the fight (no more spontaneous brawls) and there were limits to what you could use in the fight.
As regulated duels became more common, the facial wounds students received became an indicator of courage and toughness - not unlike cauliflower ear in modern grappling. The scars were also distinctive which gave each student their own unique mark to distinguish them from their peers. This became such an important part of the ritual that over time, dueling became less about fighting and more about getting a scar. The gradually evolved to facilitate wounds on very specific parts of the face and head.
And it worked!
Ever wonder why there were so many Nazis with perfect badass facial scars? Did I mention that this practice was most common in Germany?
...and it's still practiced today in universities.
Modern academic fencing, the Mensur, is neither a duel nor a sport. It is a traditional way of training and educating character and personality; thus, in a mensur bout, there is neither winner nor loser. In contrast to sport fencing, the participants stand their ground at a fixed distance. At the beginning of the tradition, duelers wore only their normal clothing (as duels sometimes would arise spontaneously) or light-cloth armor on arm, torso, and throat. In recent years, fencers are protected by chain mail or padding for the body, fencing arm, fencing hand (gauntlet) and the throat, completed by steel goggles with a nose guard. They fence at arm's length and stand more or less in one place, while attempting to hit the unprotected areas of their opponent's face and head. Flinching or dodging is not allowed, the goal being less to avoid injury than to endure it stoically. Two physicians are present (one for each opponent) to attend to injuries and stop the fight if necessary.