Zhang Fu was the mentor of the current sect master, Xu Hong, while Xu Hong was the master of Jian Yi. Therefore, in terms of seniority, Jian Yi indeed ought to address him as grand-master.
Furthermore, over the years, Zhang Fu had frequently imparted guidance on swordsmanship to Jian Yi.
This was the primary reason why Jian Yi had been able to grow so rapidly!
Chapter 56