From a technical standpoint, Chen Guan indeed couldn't break Shang Ziyi's skill.
Shang Ziyi's techniques could be said to have reached their peak, and coupled with his higher level, even though Chen Guan used the Blood Hand Seal, he still couldn't break the skills or the fight that only relied on technique and physique with Shang Ziyi.
To defeat Shang Ziyi, it might require a cultivator with a higher level to suppress him with absolute power to achieve victory.
Although Chen Guan's level was lower than Shang Ziyi's, he could also accomplish this feat.
The destructive power of the Pure Yang Sword Immortal was something Shang Ziyi could not resist with mere technique and physique.
The Asura Saber could also be tried, but Chen Guan did not wish to kill Shang Ziyi outright, so he did not use it.
