Previously, in the Immortality Regainment Realm, he didn't know how many masters of alien races he had slaughtered. There were indeed too many treasures in his hands, and the flying sword he held was obtained from the Misty Passage. When used, it wouldn't be recognized.
The Purple Dawn Sword, however, was different. Although it had a magical shield to alter the sword's light and aura, it was still an Earth Level treasure. He still had to follow behind Zong Zhen, and who knew if any flaws would be exposed? To be safe, it was more appropriate to use a treasure that matched his identity.
Anyway, he now appears to be in the True Immortal Realm, so a treasure of Lower Profound Grade is normal.
As for running away?
Now that he follows Zong Zhen, Zong Zhen might not necessarily use him for experiments, but if he were to run now, Zong Zhen would definitely suspect something wrong and act directly.
Therefore, he could only continue to follow.
