Guy
Inkling
There are also cultural factors to take into account. Maybe warrior cultures like the Vikings, Mongols, or Maasai didn't view killing with the same uneasiness modern Western society does? One can only project so much of our modern sensibilities into people from the past.
This is a good point. Historians call it presentism - grafting the values and beliefs onto cultures where those values and beliefs didn't exist. For many of those cultures - and for some still existing - might makes right and to the victor go the spoils. Simple as that. I know a guy who was in the airborne. He was stationed somewhere in North Africa and could clearly watch the goings-on in a village adjacent to him. He was under very strict orders not to interfere with anything that happened in that village. He watched one woman walk up to another and snatch a broom from her. The other woman went to her house, came back with a machete and hacked the broom thief to death. He said this experience taught him just how cheap human life is in the third world. One of the official reasons Rome held gladiatorial games was to remind people that the empire was built on blood. The thought was watching actual bloodshed kept the Roman people strong. Mercy was considered weakness of character. As far as Vikings and Germanic tribes went, if you weren't willing to fight for something you didn't deserve to have it. The accepted way for a young man to make his way in the world was through conquest.
I don't think PTSD was as big a factor for knights as it is for us. The belief was that the knight existed because God created him to fight. He was fulfilling God's purpose for him. This is not to say they never experienced PTSD, but I suspect it wasn't as big a problem as it is for contemporary soldiers. Nowadays we have a somewhat neurotic approach - we train soldiers and Marines to be professional killers, all the while telling them how wrong and horrible it is. Moreover, while we spend a great deal of effort and money in training them how to go from civilian to military life, we do nothing to help them reintegrate back into civilian life. I heard somewhere that, after taking fathers, merchants, and craftsmen and teaching them to be warriors, the ancient Israelites would, after the battle, separate these men from the rest of the population for several days of ritual cleansing, which took warriors and taught them how to be fathers, merchants and craftsmen again. I always thought that was a very wise approach for any culture that didn't have a permanent warrior caste.