During the MoP beta, this was taught by http://www.wowdb.com/items/87750-schematic-g91-landshark. This was later changed to be taught by the profession trainer.
Ignoring the botched tooltip, this item is absolutely useless. It doesn't inflict enough damage to justify the cooldown (let alone the once per combat restriction), using it puts your potions on CD, and it doesn't even have a sell value. Don't buy it from AH, don't bother crafting it for skill-up, and don't bother looting it.
Yes, G91 Landshark is that bad.
The cast time is annoying, too—a systemic problem in Engineering. :\