Runeblades (5e)

From the introduction: Runeblades are among the most powerful weapons ever forged by mortals, though the secret of their construction is nearly lost. They are empowered by ancient true runes, sigils of ineffable power that have defined the nature of reality since long before any language or society existed to try to understand them. A character may find a runeblade linked to their destiny early in their career, even have said weapon be the cause of the circumstance that makes them.