There's a trinket item which drops off a rare in the valley of the four winds called Dynasty of Steel. It's looted from Nal'lak the ripper at a roughly 20% drop rate. Dynasty of Steel - Item - World of Warcraft
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The pet itself is a whirling mass of blades that use one attack, bladewind an aoe. It seems to do 7-10% of my damage on a single target and considerably more when involving AoE situations. The trinket is on a one hour cooldown but the pet lasts for 10 minutes when called. It can only be used in the field but would be very useful in everything from a questing helper to tackling the world bosses which a lot of people are getting stuck into right now.
The exploit? It can be used from your bag to summon the pet and another trinket can be equipped without dismissing the pet. Very unlikely this is working as intended given how powerful the pet is, already giving competitive damage for an ilevel 400 trinket.