If he were to try a bit harder I think he could really earn a Darwin Award. Oh well, there’s always the next time.

Or it's just a reminder to think things through a little more before doing the stupid thing. First, he needs to understand that his target might fight back. Second, he's way too close to the target. Third, he's not throwing from just outside the box so that only his arm is at risk of a throwback. Fourth, counterintuitively, he's throwing too small of an axe at the target, which is why it had enough time to spin and hit the target exactly with the butt of the handle.

With a little more experience and a lot more luck surviving these incidents, he might become just good enough to kill a giant bouncy ball.