Contrary to what most people think, the Bible does support the right to... SELF DEFENSE! Owning deadly weapons is NOT wrong, it's their misuse that makes them wrong just like technology. In America, the Second Amendment allows gun and knife ownership however provided these people use them RESPONSIBLY! At the verse above, Jesus instructed His disciples to buy swords for their self-defense. Today, people should really exercise their rights to self-defense by having a gun or a knife at home. Of course, I am in favor of depositing firearms before entering the plane or not bringing them to school BUT guns and knives are still needed for self-defense. If owning a gun is wrong then having security guards would be wrong. If learning martial arts were wrong then it's wrong for the police to learn basic karate or kung fu to help defend themselves while they are out there catching the wrongdoers as they are ordained by the LORD to do so. What becomes wrong is when one refuses to divorce the religious aspect of a form of self defense from the physical- we recommend the use of the hard/external self-defense arts over the soft/internal ones.
Here's what- there's a big difference between killing for self-defense vs. murder. For example, if a person got a gun and shot somebody out of anger and the person's life is not threatened, that's murder and revenge. However if the person shot a person who was carrying a huge blade to kill him/her and the person who's about to be attacked does a karate chop or shoots the criminal, that's self-defense. Revenge and self-defense are not each other. Matthew 5:38-42 does not mean not to fight back, it refers to anything that does not threaten physical safety in contrast to the second example above. Jesus didn't defend Himself from arrest all because it was part of the Father's plan, not that He wanted Christians to remain too passive when their physical welfare is in danger.
Also the statement that moralists don't kill or inflict harm at all is downright wrong. Why? True moralists believe in self-defense and defending the weak. In the Bible, Hebrews 11:30-40 commemorates heroes of the faith included warriors like Samson, Barak, Jephthah, Gideon and David. Also, self-defense would in turn allow protection to others. For example, the cops see a defenseless woman being raped. Would they not hit the rapist? They have to otherwise the defenseless woman isn't going to get saved. Or in a bank robbery- sometimes you have to shoot the crooks to save the people in the bank. It's all common sense really.