Grievver Weapons
From Drunkapedia
Grievver weapons were introduced during the "Koigi Ema" Live event story arc. They are very powerful Lightning rended weapons with a Grievver Slayer property.
Long long ago, when Olthoi ruled the land, there was a nomadic band of Gharu trying to seek shelter from the endless attacks.
Among them was Guthras, an exceptional mage of his time. The Ghau tribesmen were driven to seek shelter underground, where they met a powerful group of Grievver. Koigi Ema and her brood.