I think all schools should have separate gear that can only be used in the Arena for max level PvP. As of right now, I feel like the Harrowing Hoard Packs and all the new top critical and pierce gear were meant for PvE rather than PvP, but they have altered PvP dramatically. From my understanding, every new KingsIsle update changes PvP, whether it makes it or breaks it. In my own opinion, I find that reaching 100% critical, or 100% damage, or 100% resist to a school, etc. is too much to handle in PvP. We need gear that limits us on stats but is necessary to use, just like the Commander or Warlord gear.
My own ideas are that each school should have an offensive or a more defensive side of gear given from Diego. There hasn't been many gear options for wizards to choose, as Hades+Khrysalis gear or Jade+Khrysalis gear has been the dominant setup in today's age. I feel like there should be many more gear options to choose from, given by Diego, that helps all play styles fit into the Arena, whether it be a glass cannon, a control wizard, a tank, or even a minion player.