Duan Muxiao obtained this secret technique in his early years, but when he started practicing it, he found it increasingly challenging to continue. No matter how hard he tried, he couldn't persevere.
Apart from the limited compatibility between Duan Muxiao and this Judgement Eye technique, the crucial factor was that practicing the Judgement Eye required simultaneous cultivation with other complementary techniques to reach its pinnacle.
However, Duan Muxiao only acquired the Judgement Eye and didn't obtain any of the associated techniques.
Chen Fei, on the other hand, had a breakthrough panel and didn't require other complementary techniques. Even so, it took Chen Fei quite a long time to eventually reach the state of perfection in practicing the Judgement Eye.
The Judgement Eye shared some similarities with the Sword Return Eye; both involved some elements of causality.
