From the dejected demeanor of the middle-aged man, the fact that he used a Sixth Rank Sword Master's prowess to perform a sword technique that even a Sword Saint might find challenging indicates that there is indeed a price to pay; his Qi is nearly exhausted.
Han Yan was curious about what kind of strange and mysterious arts he used. She had seen plenty of such arts before, but had never encountered one that could enhance so dramatically without relying on elixirs or other Heavenly Materials and Earth Treasures, solely through one's Qi.
Even Nian An Yao's Beastly Heart technique sacrifices life span as the price and relies on the strength of the Dragon Whisker Thunder Beast to merely elevate from a Sixth-level Sword Master to a combat power equivalent to a Sword Saint.
