I don't condone violence.
But if I did, I would sharpen the bottom edges of the star with a knife sharpener. Imagine the fellah yanking up with all his might on what turns out to be a razor edge. Bloody, and you could collect the fingers as trophies.
My electronic-engineer friend suggested wiring it up to the battery with a cap. Electronics are beyond me, but it seems like a more elegant solution.
(not responsible for your actions)