Few know of this blade’s existence, fewer still understand its cost.

When this weapon was first uncovered, its nature was dismissed as inert, its power whenever used, forgotten. It was only later that the truth revealed itself: to wield the blade is to begin erasing oneself. A god would eventually deliver this revelation to one of its bearers. Which caused the owner to come to the conclusion, This weapon does not merely wound it unmakes. Anything struck by it is permanently scarred, reduced beyond recovery, to the point that not even the wish spell could restore what was lost. A merciless force of annihilation. The former master who discovered this, in arrogance, believed himself to be capable of enduring its price. The blade answered by devouring his mind, stripping away his memory, identity, and will until nothing of the man remained. With its wielder erased, the blade vanished into legend once more. 

This weapon grants a +3 bonus to attack and damage rolls. Damage dealt by this weapon ignores resistance and immunity. The weapon deals an additional: 3d8 slashing damage when wielded in one hand, or 3d10 slashing damage when wielded in two hands, and has the Finesse property. Damage dealt by this blade to a creature also permanently lowers that creature's maximum Hit Points. Hit Points destroyed this way can never be recovered. If a creature's maximum Hit Points is reduced to 0 then memory of the creatures life is permanently destroyed.

Each time the wielder makes an attack with this weapon, they gain one level of exhaustion, as their mind tries to hold itself together and a fragment of their memory is destroyed (DM discretion on narrative effects). Sneak Attack damage dealt with this weapon does not reduce a creature’s maximum Hit Points. If this blade causes a creature to hit maximum exhaustion, instead of dying, the wielder becomes a husk of who they used to be under the DM's control.

Exception: If the attack is a critical hit, Sneak Attack damage does reduce maximum Hit Points as normal.
When this occurs, the wielder gains two levels of exhaustion instead of one.

Proficiency with a Longsword allows you to add your proficiency bonus to the attack roll for any attack you make with it.

Notes: Bonus: Magic, Weapon Property: Finesse, Damage: Slashing, Damage, Combat, Versatile, Sap