Legend of the Northern Blade

A brief description of the manhwa Legend of the Northern Blade: 
As the world plunged into darkness, martial arts masters gathered to form the “Northern Heavenly Sect”. Thanks to it, people found peace and tranquility again. Over time, however, martial arts masters began plotting against the “northern celestial sect”. Eventually, this led to the death of the cult leader, Jin Kwan-Ho, and the destruction of the cult with him.
When everyone left the cult, Jin Kwan-Ho’s only son, Jin Mu-Won, stayed with the cult. Mu-Won never studied martial arts, but one day he finds the “Martial Arts Technique” secretly left by his father. He starts studying the martial arts of the Northern Heavenly Sect…