This sword is the most powerful attack of Chu Yifan's life. As well as being in the Sacred King realm and employing his sword intent, he used two secrets that only the Sect Master has the right to know:
The Sect's Inheritance: A high-grade sacred sword.
The Heavenly Sword Technique's Second Move: Hurricane of Swords.
Yes, the Heavenly Sword Technique has a second move. Only when Chu Yifan became the Sect Master did he obtain the right to practice this part of the technique.
Even then, the Heavenly Sword Technique practiced by the Sect Master only has two movements, corresponding to the Sacred and Sacred King realms.
If there were a third movement, it would correspond to the Great Saint realm.
Imagine the destructive power that Chu Yifan could unleash by combining the high-grade holy sword with the third movement of the Heavenly Sword Technique.