Generally a fairly balanced build between offense/defense is the best, as has been said. For a dodge build, it helps to put a little more into dodge than into the weapon, until close to the end, when you can pretty much dump everything into dodge. Also don't forget you can increase you skills during combat, when you kill someone you immediately get skill points for them, and also you get bonus points for reaching ranks after you talk to the arena master. I always save before I allocate my points, so that if I have trouble in one area or the other during the battle I go back to the save and re-allocate. I've had a pretty easy time with dodge/hammer, except the Ordu, but they're also easy using the right strategy.
in the new (R2) build. Yesterday I almost beat them, but I screwed up with the spearman. I think I might have figured out how to do it, I'll try again tonight. Edit: It's also crucial to remember to loot the equipment off the fallen bodies.