I think the PVP system could use some adjustment.  The way it works right now, there's mostly only one thing that matters: Power Rating.

Now, I understand power is the goal of the game, but I've got a suggestion that will allow people who are very skilled for their power to still have a chance of earning at least a semi-decent arena ranking, regardless of power level.

Here's my suggestion:

Revise the reputation gaining system to be affected by the difference in power level.

PVP Reputation: The current reputation system is pretty much entirely in favor of the most powerful players. With your gains being based only on reputation, not power level, players who are good for their level are not rewarded with gaining more reputation.

Players should gain reputation based on power level difference, percentage-wise, with the impact being twice the difference in percentage. For example, if you win against someone with 20% less power than you, you will gain 40% reduced reputation. Against someone with half of your power, you will gain no reputation at all. Against someone with 50% more power than you, you will gain 100% increased reputation, but of course beating someone with 50% more power would be incredibly difficult. This would also affect reputation lost, with you losing more reputation from losing to someone with less power than you, and losing less reputation when defeated by someone with more power than you.