I very much agree with this distinction. Although my posts may lead people to think otherwise, I am not advocating a "stand there and take it" response to violence. I would say that its OK to "fend off blows", or to try to "disarm", even through physical actions. But, as I think you are saying, once you cross the line to one where you make the injuring of your opponent the objective, then I think you have gone too far. I recognize this "line" is not clear in many situations. But I am not suggesting that people "let themselves get punched".
You never once stated that, instead when I said I wouldn't let my children be punching bags which equates to "let themselves get punched," you just kept going on and on about how we're not supposed to anything because Jesus never did.
I think had you stated this from the start, this thread wouldn't have gone 15 pages.
My intent with my defending myself was never to harm anyone, it was merely to show that I wouldn't be a punching bag anymore. My children while having been taught to defend themselves know that they aren't to hurt the attacker unless necessary in order to defend themselves and to keep from getting seriously injured.
My son, when he defended his little sister merely tackled the boy, and wouldn't get off of him till he promised to never bully his little sister again.