Essence of Anguish is only useable as WD as your Weapons needs to roll on poison damage to work with this Shard.
Other Classes which can deal poison damage with the Gem of Efficacious Toxin, don’t proc the shard, rendering it almost useless.
Also depending on the Class used, both of them can scale extremely high. Meaning unless its a Shard intended for WD only it needs a fix.
a Demonhunter with 5% cooldown reduction gains atleast 75% cooldown reduction, if the shard rolls good this can increase to 125% (by dealing poison damage the cd reduction can increase to 15x + 5% for every enemy hit with poison max 10 stacks so +50% total). The 50% extra damage recieved is neat, but in case of a fix should be increased (my opinion).