violence is a term that means different things to different people, including people who would use the same label (like "anarcho-pacifist"). I have had people argue that violence isn't violent if it is just directed at property (I think that is bullshit, personally). I have also had a ridiculous conversation with an anarcho-pacifist who, in referencing some ELF actions back in the day suggested it might've been more tactically effective to spray paint a message on the hoods of the cars instead of burning them. Then he retracted - spray paint was too violent. Maybe they could just have a sign and sit next to the cars to communicate their message?
In a world where non-violence/violence means anything from spray paint to busted windows to newspaper boxes in the street to the satellite precision of a drone blowing up a birthday party, trying to universalize a definition seems really unimportant. I would rather that anarchists embrace that there is violence, and that we sometimes employ it, in varying degrees.