WoWDB

"The rituals for desecrating a fallen opponent are a well-established part of Mogu culture."

TIL Mogu teabag their dead opponents.

Seriously, though, not well-designed for PvP.  Using the item does not incur a global cool-down, but the window to land a killing blow is so small that you'd need to macro it to something like  Kill Shot or  Execute (as examples) for best effect.  Then, consider that your character is not under your control for 5.5 seconds.  Maybe you can get away with that in a battleground, but a RBG or arena? I say nope.

In Warlords of Draenor, this item will be added to the new Toy Box feature and no longer take up a bag slot.  You will be able to "use" the item straight from the Toy Box interface. 

The Toy Box will be account-wide and therefore so will this item.