This onyx longsword has a sharp silver edge and is inscribed with ancient runes written in elven. The runes state " In order to preserve life, one must accept death."

Attunement. In order to attune to the weapon, you must spend a long rest with the weapon within reach. At the end of the ritual, you must accept death by joining the ranks of the dead. If proven worthy, you will be called to become a Reaper and return to where you initially died.

Reaper. By becoming a Reaper, your skin color becomes paler upon a DC 15 Perception check. Your eye color becomes slightly duller (DC 20 Perception). And finally, your veins lack a pulse and some, especially near your sword wielding hand appear black. You also occasionally forget to breathe, especially in your sleep (DC 10 Perception) 

Sentience. This lawful neutral weapon has an Intelligence of 16, wisdom of 14, and charisma of 18. It can speak telepathically to its wielder. It can speak and understand common, undercommon, sylvan, elvish, and draconic. It can also understand any language the wielder understands.

Personality. The spirit inside the sword is a gold dragonborn by the name of Zarish the original forger of the blade. He sees most deeds as being necessary rather than outright good or evil. He is happiest when being wielded in service of those who are Reapers.

Cold death. This weapon has learned to harness the coldness and the life draining of death to increase its own damage. On a successful melee strike the target takes an extra 1d8 cold and 1d8 necrotic damage.

Return again. This weapon deals an additional 2d8 radiant damage instead of Cold death damage. Additionally, while facing undead you critically strike on any roll 18-20.

All things end. The blade knows all things die and must come to an end in order to keep balance. On a critical hit to a creature it suffers a point of exhaustion and the wielder absorbs half the damage dealt as hit points regained. If the blade kills the creature the wielder gains temporary hit points equal to the hit point maximum of the slain creature.

Dark Blessing. While holding the sword, you can use an action to give yourself 1d4 + 4 temporary hit points. This property can’t be used again until the next dusk.

Disheartening Strike. When you hit a creature with an attack using this weapon, you can fill the target with unsettling dread: the target has disadvantage on the next saving throw it makes before the end of your next turn. The creature ignores this effect if it’s immune to the frightened condition. Once you use this property, you can’t do so again until the next dusk.

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, Damage: Cold, Damage: Necrotic, Damage: Radiant, Versatile, Sap