Kids know the difference between right and wrong, and self defence is not violence.

They literally play games that involve cops and robbers, super heroes and villains, and you want to say they wouldn’t understand the difference between violence and self defence? They already understand quite well that playing isn’t violence. Why do you think self defence is this impossible step?

You’re teaching them to stand up for themselves, not to go out and be bullies, why are you assuming and loudly claiming that’s the only outcome?