Blade of Light and Shadows

Weapon (longsword), rare (requires attunement)

This item appears to be a Longsword hilt. While grasping the hilt, you can use a Bonus Action or your object interaction to cause a blade of pure Radiance to spring into existence, or make the blade disappear. While the blade exists, this magic Longsword has the Finesse property. If you are proficient with shortswords or longswords, you are proficient with the Blade of Light and Shadows. It can also be used as a spellcasting focus.

You gain a +3 bonus to Attack and Damage Rolls made with this weapon, which deals radiant damage instead of slashing damage. When you hit an Undead with it, that target takes an extra 1d8 radiant damage.

As a bonus action, or as a part of the bonus action you use to make the blade appear, you can cast the spell Shadow Blade without expending a spell slot. Once you use this ability, you can not do so until the next dawn. The spell is cast at your highest spell slot if you have spell slots or pact magic feature, or second level if you do not. When you cast the spell using this feature, or you cast shadow blade while attuned to the Blade of Light and Shadows, it does not require concentration and lasts for 8 hours.

The sword's luminous blade emits bright light in a 15-foot radius and dim light for an additional 15 feet. The light is sunlight. While the blade persists, you can use an action to expand or reduce its radius of bright and dim light by 5 feet each, to a maximum of 30 feet each or a minimum of 10 feet each.