I'm not exactly sure at what age young boys start to grasp the concept of weapons, but based on what I've seen with my boys, it must be fairly young. I'm guessing it has something to do with watching too much television, and I'm not sure what exactly that says about me as a parent. I think it would be a lot cooler if it were due to some inborn mode of survival. As you can see by the look on my 3 year old's face (as he's about to attack me with a plastic sword), he definitely has a killer instinct. Who knows, maybe someday he'll rule the world.