Excalibur

''This sword glows with a holy yellow light and leaves a trail of harmless sparks of the same color when swung. However, the sword's true form is that of a small white dog-like creature that stands on two legs, and carrots a top hat and cane. It speaks in a dulcet tone, and thinks very highly of itself.''

Any sword, requires attunement.
+3 Weapon

Excalibur and prepare and cast spells as a 10th level paladin with the Oath of Devotion (+7 spell attack, DC 15). To convince the sword to cast a spell, you must use an action to make a DC 18 persuasion check. You have advantage on this roll if you really inflate his ego while doing so.

Excalibur is Lawful Good, has 14 Intelligence, 6 Wisdom, and 17 Charisma.

Legendary
Excalibur has been wielded by many adventurers over hundreds of years, putting him on the frontline of many famous historical conflicts and triumphs. He has witnessed firsthand some of the most iconic moments in history, and is a horribly unreliable storyteller because of his massive ego. Listening to Excalibur tell you a tale is... grating to say the least. He always puts himself at the center of attention, and always claims to have accomplished or been responsible for pretty much everything single-handedly, despite in fact, being a sword. Banishing Kazaarlex the Betrayer? Excalibur did that while the other gods assisted him. Killing Q'gardaron the Elder? Excalibur was the primary sword and Burjion was wielded in the off hand, and barely got used. Ioun the Supreme Judge? Why, Excalibur taught her everything she knows. He's an undeniably powerful weapon, but putting up with him makes most adventurers return him to another spot, always embedded in a stone.

When used in combat Excalibur will loudly proclaim that he is the best, thanking the party for assisting him, or otherwise shouting out taunts to his foes, or an ally that fails.