Ashrune

With this longsword, all you have to do is open your hand, and it will appear in your hand once attuned to it.

You have +5 to attack and damage rolls with this magic weapon.

Ashrune also lets you cast the magic missile spell at 7th level at will and deals an extra 3d10 lightning damage when physically hitting the target.

You also gain immunity to lightning damage, but becomes vulnerable to thunder damage. You gain a +1 bonus to AC as Ashrune guides you in battle and gain proficiency with longswords.

Ashrune has sentience and is of the true neutral alignment. Ashrune can talk to you and your party telepathically regardless of whether or not they're in your hand.

Proficiency with a Longsword allows you to add your proficiency bonus to the attack roll for any attack you make with it.

Notes: Bonus: Magic, Damage: Lightning, Immunity: Lightning, Vulnerability: Thunder, Bonus: Armor Class, Proficiency: Longsword, any neutral alignment, Damage, Combat, Versatile, Sap