Elis'vor, The Incandescent

Weapon (glaive), legendary (requires attunement by a wielder with a Lawful/Neutral Good alignment)

Elis'vor was once a paladin long ago who lost a battle to a malevolent beholder. This creature tortured her soul for ages before she was eventually sacrificed over a blade of unknown materials. In hopes that the weapon would become a tortured, crazed living glaive, the beholder willed her broken soul into the staff.

Some unknown amount of time after the weapon had been created, Elis'vor found her sanity and understood she must purge her hatred and wickedness from her still-living soul. The Messengers of the Bean found the weapon and helped Elis'vor transform from a bloodthirsty weapon into a righteous defender.

The specific chronology of the weapon's lifespan is unknown, but it can be assumed that the weapon is ancient to the highest degree. While she is still an immortal soul, she does not remember every detail of her existence.

Stats from DANDWIKI
An exquisitely crafted blade, Elis'vor's shaft is the purest white that cannot be dirtied, an intricate pattern that glows like the morning sun decorates the entirety of the shaft, the blade itself has a menacing glow and is pitch black. Upon entering the Underdark the blade changes color and emits a soft glow similar to that of the shaft of the blade emitting dim-light in a 20 foot radius. The weapon always feels comforting and warm to the touch. The user gains +2 to all attack and damage rolls and the weapon has the following properties:

Know thy enemy
Elis'vor has spent it's entire creation hunting creatures of an evil nature. If the user manages to land an attack on any creature that is inherently evil the creature must then make a DC 17 Constitution saving throw. On a failed save, Elis'vor will then telepathically inform the wielder of the type of entity and it's immunities, resistances and weaknesses they have just struck.

Fear the Rising Sun
Undead and Fiends recoil from the light that Elis'vor expels, these creatures take 1d6 radiant damage when they enter within 20 feet of the weapon or end their turn within that radius.

Only the Unholy
If the wielder attempts to kill any entity whose alignment is Lawful/Neutral Good, then Elis'vor immediately causes it's wielder to miss. If this occurs 5 times, then the wielders alignment shifts to Neutral and Elis'vor unbinds itself and deals 6d10 radiant damage to it's now ex-wielder. The ex-wielder can never re-attune to the weapon and if they continue to try and use it as a normal weapon Elis'vor punishes them resulting in disadvantage on all attack rolls.

Light's Justice
The user may slam the butt of Elis'vor into the ground and call upon the might of the Sun. The wielder may casts the sunbeam spell with no material or somatic components as an action. If the wielder is not inherently a spell-caster, then the spell save DC for this spell is 15. This weapon regains use of light's justice at dawn.

Fear is in the Eye of the Beholder
Due to the history of the soul inside Elis'vor has an innate fear of beholders and will cease to communicate until the being is out of sight or dead. Negating the Know thy enemy ability and her pain and suffering inflicts the user with disadvantage on Wisdom saving throws and Concentration checks while within visual range of a beholder.

Sentient weapon
Elis'vor is a sentient Lawful Good weapon. It has hearing and darkvision up to 50ft and truesight up to 10ft. It can speak Common, Elvish, and Sylvan, but can also understand any language it's wielder knows. Elis'vor can only communicate telepathically to her attuned wielder and any being deemed a friend or ally of her within 50ft radius.

Righteous Soul
Elis'vor contains the soul of a female elven paladin from many ages past. Captured and tortured for almost 300 years by a beholder before being sacrificed in an attempt to make a powerful and malicious weapon. Elis'vor managed to retain her sanity and in her sacrifice her chosen deity blessed her soul imbuing her and transforming the weapon destroying it's corrupt nature and making it into a weapon of holy vengeance. The wielder will often see visions of Elis'vor's traumatic torture and her resolve against it in their dreams. Elis'vor is kindhearted but is quick to unleash her fury in battle with evil and will often give commands to her attuned wielder and others in their party in order to quickly destroy the evil presence. If the wielder goes 7 days without rooting out evil in one way or another, then a conflict between it and its wielder occurs at the next sunset.

Stats
Intelligence: 14 (+2)

Wisdom: 16 (+3)

Charisma: 20 (+5)