I've seen Reese's handling with his nephew and I must say that the possibility of this scenario is not far fetched. I could totally see Reese handign a hammer to a small child and saying "Have at it!"

I'm not sure I would tell a child to hit someone with a hammer. I would probably teach them to use a hammer and let them hurt themselves and learn from it. Then they could put it all together themselves and figure out that the hammer could be used as a weapon against those they dislike. It's more of a learning experience then.