Jeoldaegeomgam

For as long as he can remember, Woonhwi So has been the black sheep of his family and clan. Because his spirit core has been destroyed, he has no choice but to serve as a third-rate spy for the Blood Cult. One day, during his mission to find the legendary Blade Scroll, he is killed and sent 10 years into the past. When Woonhwi regains consciousness, he realizes that he has been sent back to the day he was kidnapped by the Blood Cult, and that he has gained a mysterious ability to hear the voice of a dagger.

(Source: Webtoons)