With the ability to use violence there also is a big responsibility to use it right.
"With great power, comes great responsibility".
Quote: Spiderman's Uncle Ben Parker
It is always your opponent/threat that dictates how much violence you should use to defend yourself.
If the threat is lethal, and you are standing in front of two guys, one with a knife, then you must hit hard and in places where it will help you gain time and hopefully end the conflict quickly.
“You are the weapon, everything else is just a tool” (Ref. 7).
Be aware that there is a risk of not just hurting but acutely ending a person’s life if the windpipe collapses.
You must live with this and with the consequences as well.
If the threat you are standing in is not lethal, then don’t go nuclear.
If you have the overhand, take control with a firm domination with pressure from start to end.
“The paradox of courage is that a man must be a little careless of his life, even in order to keep it” (Ref. 8).
Train for both situations, to deliver many attacks that badly hurts or to control your opponent without hurting them to much (soft methods)
If the man is down, then he is down. Stop!
If he is moving, how he moves is what is important. What is the circumstances?
If he got up and attacked again, you maybe could do something else. Is it likely that he would run? or get back up and yell, or with he stay down and curl?
You have to know when to stop.
Don't carry a knife if you aren't willing to pull it. Don't pull if you aren't willing to use it. Don't use it if you're not willing to kill.
Don't kill, if you aren't willing to take the punishment.