This item appears to be a longsword hilt. While grasping the hilt, you can use a bonus action 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 sun blade.
You gain a +2 bonus to attack and damage rolls made with this weapon, which deals force damage instead of slashing damage. When you hit an aberration with it, that target takes an extra 1d8 force damage.
The sword's astral blade emits bright light in a 15-foot radius and dim light for an additional 15 feet. The light cuts trough magical darkness. While the blade persists, invisible targets within the lights radius become visible by glowing a bright blue.
Proficiency with a Longsword allows you to add your proficiency bonus to the attack roll for any attack you make with it.
This weapon has the following mastery property. To use this property, you must have a feature that lets you use it.
Sap. If you hit a creature with this weapon, that creature has Disadvantage on its next attack roll before the start of your next turn.
Notes: Bonus: Magic, Damage: Force, Replace Damage Type: Force, Weapon Property: Finesse, Damage, Combat, Versatile, Sap