You're conveniently ignoring motives here. If the lunatic adult is wielding a knife because (he claims that) you took his house and land and started living in

You're conveniently ignoring motives here. If the lunatic adult is wielding a knife because (he claims that) you took his house and land and started living in it and don't want to leave, then do you still think it's acceptable to hit him? It seems to me that you're oversimplifying the situation. Nothing is black and white, and certainly not the Israel-Palestina conflict.