I'm really impressed with this one. The idea of unconventional weaponry was not in the novelty of the method of killing, but the outlandish and heretical nature of the device that the main character leveraged. It's an unexpected twist on the theme of the competition that works so well.
A concise work, effectively written in first person. We don't even get the name of the main character, which adds to the sense that he's been stripped of his former life.
I've tried to include at least on recommendation for improvement with each story I've read. After reading this a few times, I really don't have any recommendations. Bravo on such a well-written piece!