Nightbringer

From Syra D&D Wiki

Nightbringer is a sentient longsword. Formerly wielded by Zirithian - a drow who sought to become an exarch of Orcus - it was claimed by the Challengers of the Unspeakable upon the death of its owner. Orcus appeared and demanded the blade, but the sword spoke to them, urging them not to give it to the demon lord. When it promised Harthur Grai the power to slay his foes in combat, the ranger decided instead to keep it for himself.

It is unknown who created Nightbringer, but it insists that it was merely found by Orcus, not forged by him.