Eris

"Strife herself once stole away with it, such was its destructive allure."

- Lore

Eris, Roman Discordia, in Greco-Roman mythology, the personification of strife. She was called the daughter of Nyx (Night) by Hesiod, but she was sister and companion of Ares (the Roman Mars) in Homer’s version. Eris is best known for her part in starting the Trojan War. When she alone of the gods was not invited to the marriage of Peleus and Thetis, she threw among the guests a golden apple inscribed “For the most beautiful.” Hera, Athena, and Aphrodite each claimed it, and Zeus assigned the decision to Paris, then a shepherd on Mount Ida. Paris awarded the apple to Aphrodite, who then helped him win Helen of Troy. In the war that resulted, Hera and Athena remained implacable enemies of Troy.

Hades
At some point after the Titan War, Eris stole the Adamant Rail from the goddess Hestia and planned to use it to sow chaos. It's unknown exactly what happened during this period but eventually the weapon would end up leaving her possession in favor of Zagreus.

Additional Notes
For additional information on Eris that does not pertain to Hades, see Wikipedia's article: Eris