What is the meaning of the sword spirit in The Legend of the Fairy Sword and the Chivalrous Man?

A boy as sharp as a sword, a soul as clear as the sound of a piano, a distant scenery, a dancing soul bird, a sword and a heart tell a legend that never regrets. I think it means Baili Tusu.

I don't think even Qin Xin is Ouyang Shaogong. After all, it was Tu Su who finally completed the agreement between the prince's dulcimer and Yu Zhan. Ouyang Shaogong's last appearance has completely abandoned his status as a "piano fairy" and is not worthy of the word "Qin Xin".