Tartanos

"Don't forget, Sakray. Your curse is not lifted yet! Until you find the blood that will satisfy me, your soul is mine!"

- Tartanos

 (Korean: 타르타노스) is a sentient weapon that drains the blood of whoever it injures and receives the memories of that victim. As such, can learn the fighting techniques of the person it drains the blood of, as Sakray stated in Volume 10.

In some publications of the manhwa, this weapon is known as Talatsu or Talefing. On iRO, this weapon is localized as Thanatos.

Background
explains that he was forged by the gods, but the gods feared his power and so sealed him underneath a castle. There waited for a worthy individual to wield him. After Sakray surrendered his soul to him, reveals that it was the knight's destiny to wield him and that he had been waiting specifically for Sakray to appear.