Over at Shushan, Qiu Changtian's task in the Ling Yunpo swordplay competition was to defeat Duan Fenhai and secure the second rank on the Immortal Sword Ranking, which he did successfully.
The next goal was to hold onto that second rank, which required striking down any challengers with thunderous might, to ensure no one else dared attempt a challenge.
This "thunderous might" was quite literal in meaning.
The Postnatal Five Elements Great Extermination Divine Light was too domineering, turning a Flying Sword into scrap metal with a single brush.
It looked unharmed on the outside but was devoid of spiritual essence within, something anyone could detect as being amiss.
Only the Five Thunder True Law could deceive with the Daoist magic sealed within the Thunder Punishment Sword... after all, no one knew which Daoist magics were sealed inside it.