Starfire Katana

Weapon (longsword), legendary (requires attunement)

This weapon appears as a silver katana hilt. It functions as a sun blade, except that its bonus to attack and damage rolls is +3. This weapon is said to have been the inspiration for the first sun blade, but its craftsmanship remains unmatched even millennia later. Its blade is made of pure starlight, and its edge is the breadth of a ray of light. The blade was first forged by an archfey who managed to contain the shimmering starlight—by complete happenstance—by correctly guessing the light's true name as it streaked towards the horizon as a shooting star.

Starlight Arc. When you take the Attack action on your turn using this weapon, you can forgo the first attack you make to cause the blade to emit an arc of light, which travels until it reaches the nearest creature to you in a 30-foot cone; if multiple creatures in the cone are equidistant from you (such as a pair of creatures standing next to each other), it reaches each of them simultaneously. Make a single melee attack with the blade, using that attack roll against each target the arc of light reached. On a hit, a target takes an extra 1d8 radiant damage from the attack, and any illusions on it are magically ended. Hit or miss, the arc of light dissipates after the attack, and any other creatures within the cone are unaffected.

Sunburst. You can use an action while holding the katana to cast the sunburst spell from it (save DC 15). This property can't be used again until the next dawn.

Sentience. The starfire katana is a sentient chaotic good weapon with an Intelligence of 8, a Wisdom of 13, and a Charisma of 17. It has hearing and darkvision out to a range of 120 feet. The weapon communicates telepathically with its wielder and can speak, read, and understand Celestial, Common, and Sylvan.

Personality. The starfire katana is interested in the goings-on of the Inner Planes. It sees the endless push and pull of forces, especially in the Material Plane, like a living and unpredictable ocean tide. Its personality is bound to the light it emits, and it has spent millennia simply careening through the stars. As a result, even the mundane happenings of civilization can still fascinate the sword. When given a choice, it prefers to steer the tide against the forces of evil, but it acknowledges fully that "evil" is a matter of perspective and time, of which it has much.

The arch fey strode through the glen, unbothered by the eyes leering at him from the shadows. Theirs were the hungry but bestial glares that knew, instinctively, that this traveler was not to be troubled. They were right, of course.
Streaks of hurried starlight swept across the inky sky above. He always loved these; it was enough to make him tolerate the stink of the Material Plane from time to time. Magic could be found everywhere, and on the Material, his favorite magic was found amongst the heavens.
He named the first light he saw Levaestra, for its tail was wavy and warm like his old cat, of the same name.
He named the second light Clo'esh for its cold and heavy path, a name in honor of a great beast from his homeland.
He paused at the third light, and sought a name for its warmth and brilliance. Its movement was straight, perfectly so, the way that a perfect circle is said to make the mortal uneasy. How foolish.
"Th'leel," he said, decisively. A name he liked, based on—
And the starlight winked out.
The fey found this strange, of course, but not so strange as when the light reappeared before him, floating in space as a marble-sized orb. He stopped in the clearing. All of the sounds of the night had stopped with him.
In his mind he felt a presence, like a warm sunbeam in the back of his consciousness. He knew it was friendly and that it shared his surprise.
"Th'leel," the arch fey repeated, and the light stirred with recognition.