Blood-Tempered Ranseur

The Blood-Tempered Ranseur was the Blood Knight order's distinctive weapon. As such, many Blood Knights mobs were using a ranseur.

The creation of the blood-tempered ranseur required a variety of rare and volatile materials, resulting in a fearsome weapon of superior craftsmanship. To properly temper the metal of the ranseurs, they had to be quenched in the blood of a powerful demon.

Source
This item was a quest reward from The Blood-Tempered Ranseur.

As of World of Warcraft: Legion, players who had previously acquired the ranseur are able to find it in their wardrobe for Transmogrification, even if they had lost or discarded it prior.