Spoiler!
If I remember from the novel this is the 3rd timeline after people repeatedly changed the past. In the original timeliness Chun yeowun with 1 diving beast vs the blade master 3 utterly destroyed him with ease leaving a lasting trauma with the blade master. So much so when he fights the current Chun yeowun he said "you're not him" referring to the previous timeliness where time had to be rewritten for him to win