Dawnbringer

Dawnbringer appears to be a gilded longsword hilt. While grasping the hilt, you can use a bonus action to make a blade of pure radiance spring from the hilt, or cause the blade to disappear. While the blade exists, this magic longsword has the finesse property. If you are proficient with shortswords or longswords, you are proficient with Dawnbringer.

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.

If you attune to Dawnbringer, you gain a +2 bonus to attack and damage rolls made with her, which deals radiant damage instead of slashing damage. When you hit an undead with it, that target takes an extra 1d8 radiant damage.

Dawnbringer can communicate with it's wearer telepathically. As long as you are attuned to her, she knows every language you know. Otherwise, she can speak and understand Common.