After Caeles Strari was betrayed by his patron Sol Sultana, his rage manifested into a meeting with the god of the hells, Krros. After signing a pact with the archdevil supreme, Krros pulled the first chainsaw blade out of Caeles' head, forging it via his psyche and hellfire and naming it the "Blade of Want". It was Caeles' final weapon, replacing the sunblade Eventide.
Since then, others have also found blades such as these, leading them to be called Blades of Vaitarnus.
Weapon (Greatsword), Very Rare (Requires Attunement)
This weapon was forged in the ashtadharmic hell of Vaitarnus. Made form through the psyche of those damned to the hells, it is an unholy blade of rust and death. While attuned, you gain a +2 bonus to attack and damage rolls made with this weapon.
Psychic Whirl. This blade is telekinetically linked to its user. When you make an attack with this weapon, you can choose to throw it with a normal range of 30 feet and a long range of 60 feet. When used as part of multiple attacks, you can then direct the blade to another target within the same range of the first target, so long as the blade does not go beyond 60 feet away from you. The blade returns to your hand after these attacks, or floats in an empty space within 5 feet of you if you cannot grasp it.
Destined for Vaitarnus. While attuned to this blade, you can choose to turn any Radiant damage you do into Necrotic damage.
Chainsaw of the Hells. As an Action, you charge up the spikes with necrotic energy and thrust the blade telekinetically into a target within 30 feet of you. The target must make a DC 15 Dexterity Saving Throw, taking 3d10 Slashing damage and 3d10 Necrotic damage on a failed save, or half as much damage on a successful one. You can use this ability once per Long Rest.