So many people underestimate martial arts nowadays, as the name says, martial art are about war technic, so they were created to kill first... The Shaolin Kung-fu for example, was created to defend monks from barbarian armies, you can't justpush a barbarian, it is clear. In war, it is difficult to stop someone just by hurting him. So, most of the time people were obliged to kill to defend their own life.
So let’s be clear, martial art is first about war. There is, I believe, a dark side of it. We need to accept that Violence is a part of that art.
In some people, these experiences can be a means of personal growth. Power to control can lead to self-confidence and a very positive outlook. Seeing pain in other people (given a modicum of empathy) allows one to understand the responsibilities that go with the skills.