@failures art,
There does not appear to be objective moral values, and if there is, it may be
immaterial, therefore requires a moral law giver.
My personal opinion of violence:
If you are violent, you must be open to the concept of being subjected to violence.
Example:
If you attempt to kill, you must acknowledge the attempt for survival, perhaps being violence.
However, if you do have moral laws, such as 'no killing', it is morally self refuting to infact kill the killer.