The Explorers' League members excavating Remtravel's Excavation discovered tablets that explains the history of the Master's Glaive. The site was witness to an ancient battle, one between Soggoth the Slitherer and no less than twenty Stone giants sent by the titans. So terrible was the battle, only the largest giant, named Kronn, survived. He allowed himself to be entangled by Soggoth's tendrils -- just long enough to be lifted close enough to Soggoth's skull and within reach of his mighty sword. His sword, of course, became known as the Master's Glaive.
While it was once a night elf holy place, the area is now under the control of the Twilight’s Hammer, who has begun excavating Soggoth's remains with the intention of restoring them to life.
It is confusing why the titans would have impaled a minion of the Old Gods and left such a powerful a weapon in its dead corpse. Some theorize that the sword in its remains prevents it from regenerating and putting Azeroth in danger once again.
The term "Master’s Glaive" refers to the sword embedded in the skull, though sometimes it is used to refer to the whole site. There are rumors of a complex underground labyrinth underneath the remains.