Source: Critical Role

Weapon (greatsword), ??? (requires attunement)

Craven Edge is a sentient, thick, onyx, two-handed greatsword. Imbued with dark arcane power, Craven Edge drains strength from the foes it strikes, absorbing their blood into its blade. It may even consume the soul of its wielder.

Dark Aura. Grants the wielder advantage on Charisma (Intimidation) checks when unsheathed.

Devour the Weak. Whenever Craven Edge damages a living creature, that creature must roll a Constitution saving throw (DC 12). On a failed save, Craven Edge drains one point from the creature's Strength score and transfers it to the wielder (increasing to a maximum of 25 Strength) until the next short rest or long rest. Creatures brought to 0 Strength by this feature are slain.

Gluttonous Evolution. If Craven Edge devours enough strength from Devour the Weak to bring the wielder to 25 Strength, then the blade shifts form into a larger, jagged blade that seeps shadow. Until the wielder's next short rest or long rest, all attacks with this sword deal an additional 2d6 necrotic damage. After the short rest, the attuned creature must make a Constitution saving throw (DC 16) or have the now-hungry weapon, energy spent, devour the wielder's soul, causing instant death.

Sentience. Craven Edge is a sentient, chaotic evil weapon with an intelligence of 16, a wisdom of 12, and a charisma of 18. It has hearing and darkvision out to a range of 60 ft. This weapon can understand abyssal & common, and can communicate with anyone who's wielded it telepathically. While you are attuned to it, Craven Edge also understands every language you know.

Personality. Craven Edge is cold, vicious, and seeks violence at any opportunity. It wishes to be used by merciless creatures who will feed it when ordered to.