Blade of the Bloodthirsty

Weapon (longsword), very rare (requires attunement by a barbarian)

This +2 longsword has a handguard on its hilt that points towards the blade, giving the appearance like a ring of jagged teeth like the mouth of a leech. The blade of the bloodthirsty scores a critical hit on a roll of a 19 or a 20. As a bonus action, you can transform this weapon into a battleaxe. glaive, greataxe, greatsword, halberd, scimitar, shortsword, or back into a longsword. In addition, if you ever score a critical hit with this weapon, you deal an extra 2d6 necrotic damage to the creature you hit and heal the same amount of hit points.