Farbane

From Syra D&D Wiki

Farbane is a magical waraxe carved from a mysterious purple crystal. This material makes it exceptionally strong against aberrations, as well as providing its wielder some protection against the same. It is unknown how or where it was created, but it eventually ended up in Acererak's treasure hoard in the Tomb of Horrors, where it was found by the Challengers of the Unspeakable. It is now wielded by the half-orc ranger Harthur Grai.

During the Battle of Silverstone, when it was discovered that the stone heart of a powerful aberrant monstrosity had been implanted into Boccob's chest, Harthur used Farbane to shatter it and give the former god a merciful death. A portion of their essence was drawn into Farbane, further empowering it.