I've been PvPing a lot more lately, specifically Arenas. Some 2v2 and 3v3 matches are all DPS, making Wound Poison superfluous. However with the following macro (and an item/weapon switcher like ItemRack), you can poison a third weapon, stored in your inventory, and tie it to your Shiv ability:
/itemrack equip poisonthree
/itemrack equip normalweapons
Stab 'em where it hurts ... their mana!