The Soul Sacrificial Daggers were a blasphemous creation during the Omniborn Crisis known to destroy a target's soul for good, preventing them from having an afterlife. They were banned by the Jakunic Church.
Weapon (dagger), very rare, cursed, requires attunement
This dagger is made of pure gold, and is in the shape of a serpent. This artifact from the first era was used to rend victims of their souls, preventing them from going to the afterlife and the gods.
You have a +2 to attack and damage rolls with this golden dagger. On a hit with this weapon, you do an additional 2d4 necrotic damage. Whenever you reduce a creature to 0 hit points with this dagger, you tear out their soul and feed it to the dagger, destroying it. However, you are cursed with soul hunger while attuned to this dagger. You cannot unattune from this dagger without the use of a remove curse spell, or by sacrificing a sapient soul to feed the dagger.
Soul Hunger. The dagger, and by extension you, hunger for souls. You must feed a sapient soul to the dagger once per week, else your own soul gets consumed by the dagger, permanently killing you.