This was because the records of Chu Yunfan and Jian Wuchen were somewhat similar. Jian Wuchen was an expert in the way of the sword, while Chu Yunfan did not seem to be a cultivator in the way of the sword. However, in the records of the early years, there were records of Chu Yunfan's astonishing cultivation in the way of the sword.
From all the information, one could deduce the fact that Chu Yunfan had received the inheritance of the Violet Thunder Sword Sect.
In other words, Chu Yunfan should be a master of the sword, but his performance was not very obvious.
In addition, Jian Wuchen's lightning divine power was similar to Chu Yunfan's.
Not to mention the fact that the time when the two appeared was related. After Jian Wuchen appeared, he killed many experts of the Destiny Sect, but no one in the Destiny Sect knew who Jian Wuchen was.
