The Namgung Family's Youngest Son is a Reincarnation Hunter

Namgung Hwi, a concubine's son suffering from severed meridians. Just when everyone thought he was dead, he returned to the past. And upon opening his eyes, strange letters appeared. [You have become the Master of the Martial Arts Library.] Any martial art he sees or understands can be made his own. He can now overcome his severed meridians and trample over every single one of those damn Namgung Clan brats. “The life my mother gave me. This time, I will live it differently.”