instead of nerfing to be able to PvP, do it different.
Buff the HP with like 100x, don't nerf any skill whatsever. Bring a debuff before to all starting in the arena and for example lock the chosen skills. Create PvP shrines, like phys-immune for 10 sec. / life regen 20k per sec for 10 sec etc. and make breakable objects and such (think about the anti-rush boulders in sc2)
This is far easier to make and needs no balance or a lot of blizz work, it also gives some tactics and skill it just needs to be much less work for blizz otherwise they will never intergrate PvP at all