The game itself is really good and incredibly polished ! I find it a bit needlessly hard for a jam (I got combo'd to death multiple times, and you really need to play defensively to avoid trading hits, which is a bit less fun) but the concept is enjoyable, and I love the idea of giving the upgrade to the opponent !
The music and sounds are really nice and really convey the "gladiator feeling". Really good job !
However... I really don't see the relationship with the theme. I have read the "How does your game fit the theme?" part, but it really didn't convice me. Nothing is "joined together". In fact, if you talk about the upgrades, it's even the exact opposite, since the enemies get the upgrade we don't. If they got the same upgrade, I could maybe understand the "joined progression", but here... Sorry, but I really don't see ^^'.
Don't get me wrong, it's a really, really good game, and I would LOVE to play a post-jam version and see it becoming a bigger thing, but as a "GTMK entry", it's off-topic ^^'.