There is no ultimate skill, only the skill that suits you best.
This was what Pei Xuanjing once said to Zhao Baiyang during their philosophical discussions. Pei Xuanjing believed that any skill could only bring out its most powerful potential by its creator, just like the discipline of martial studies, because only the creator is the most suitable person.
What about a skill that leads directly to the Spirit Realm Eightfold? To cultivate this skill means giving up your current path. Zhao Baiyang naturally wouldn't want to do that.
Now he tells Zi Tianxiong that he wants the latter to understand that only the path that suits him best is the most powerful path. The Taoist Foundation should be the path that fits oneself best, so one can go further on the cultivation path.
"I understand and won't waver anymore." Zi Tianxiong said solemnly, nodding.