Awesome WD u alrdy hv there but if ure looking to improve, i would say stack more avg dmg (on both rings).. definately try craft a trifec gloves with AR & also bracer with max cc/6% (2h WD need all the CC they can get since losing 9-10cc from mojo).
In terms of skill/build .. u might want to try use bbv-slam dance to kill e pack faster (since u alrdy using mass confusion as crowd control, hex would be redundant .. plus farming high density areas, cooldown shud be no problem cos u r using Grave Injustice) @ if u feel ure dying too much, Horrify-Frightening Aspect is also a viable option to replace Hex (with ur high armor base FA will boost it even more + Horrify also act as a semi crowd control in sticky situation)
Personally i would use Spirit Vessel instead of Gruesome Feast .. not just bcos of the xtra set of life but more importantly for reduced cooldown on Spirit Walk ... as i think u alrdy know, SW is the best skill to hv always especially during channeling bats against CC elites (frozen. knockback, fear etc).

p/s: always use Horrify-FA 1st b4 using Mass Confusion .. so that the feared mobs will be confused and stay in Bats AoE range .. unless ure using Horrify to get out of sticky situation when health pool is very low.