A little while ago I have finished the main boss. I think that I have all but two or three achievements and I haven't finished any of the bonus matches. This is a really good game in its genre (that being the genre of "gladiator-fighting-rpg"). I truly liked the graphic style, music was perfect, storyline... well, it was a nice little story, nothing groundbreaking. It served it's purpose. Gameplay was nice, but sometimes controls felt a little bit unresponsive. I think I understand what you wanted to accomplish, yet I don't think it truly suits a game with such a fast paced gameplay and this much enemies on one screen. However, I still enjoyed it a lot.
I liked the weapons, with few exceptions. Main example is the "heavy" category. I didn't liked the idea of using a big cactus, but I definitely didn't liked the lightsaber weapon. Yeah, we all love lightsabers, but it just doesn't suit the overall atmosphere and setting. These two weapons would be nice as a bonus weapons, but not as a normal ones... That can be also said about obsidian shield and sword and obsidian armor. And the greek shield, paired with iconic ancient egyptian sword, yet it was called greek... This it just nitpicking, it definitely didn't stopped me from enjoying this game :-)
That being said, my only major complaint was pretty much only about controls. If there were fewer enemies on screen, then they would be alright, but when you have to fight hundreds of enemies, you want to truly feel like you are in control.
Oh, one more. The first arena was pretty easy, but then the second one began suddenly being pretty hard. It can be just me, but the difficulty curve could be a little bit more optimized. It made me change my way of playing and I had to experiment and try different combinations, so I don't think it is that big of a problem.
Yeah, this was a really good game and I hope there would be a sequel :-)