I agree violence should be a last resort. In my case, it was an issue of the school not willing to intervene. If the school is so spineless as to not intervene, they should not be able to punish a kid who defends himself. 

It's not right that adults have legal protection from physical assault and threats of violence but we let kids put up with it and just call it "kids being kids." Then wonder why some bullies become adults with violent behavior, and wonder why those bullied leave school with subpar education.