Soul of Darkness (5e Equipment)
From D&D Wiki
Weapon (shortsword), artifact (requires attunement by a character of a rogue type class with 15 Wisdom)
The Soul of Darkness was forged with the bones of a night dragon. The Soul of Darkness was created by a wizard who owed an assassin a favor, this assassin became the first Shadow Assassin. He used this blade to defeat anyone who stood between him and his target. Then one of his targets, a powerful wizard, heard of the power within his sword, so the wizard constructed The Shard of Radiance to fight the assassin. But when the assassin died, the blade was lost to the Plane of Shadows. The sword binds to its user's soul granting lots of ability's. It grants +3 to attack rolls and does an additional 1d8 necrotic damage. You cannot be disarmed of this sword by an opponent without a powerful Holy Symbol or radiant artifact weapon. You can conjure the sword through a nearby shadow, so there must be light. The blade can be melted down and infused into other equipment while keeping some of the abilities, but if it the new equipment comes into contact with the shard of radiance, all properties will be lost, of both Soul of Darkness and whatever other equipment it is infused with.
Shadow Step. While you are holding the sword, you are able to travel a distance using the Shadowfell, and the shadows that smudge the barrier between the two planes.You magically teleport 30ft along with all the equipment you are wearing or carrying, so long as you are in dim light or darkness, and the area you are going is un occupied and in dim light or darkness.
Shadow World. This blade has the ability to create darkness, everyone within 60 feet of the sword gets surrounded by complete and total darkness, once this power is used you cannot use it again until next dawn.