Just because you have a weapon doesn't mean you only use it for the purpose of hurting. My weapon while it can change into a sword doesn't actually hurt anyone. It's purpose is different. It just depends on how you use it.

Or you can think of it in another way. While I am very much against killing... believe me the thing I just mentioned came about because of my unwillingness to kill people. I have to learn to think of other ways to help save someone, even if it does mean having to hurt or kill. But those are more last resort.