Emei Sect's Divine Yang Skill was not written in paper form and passed down through the generations, but was instead verbally shared from master to student.
Happy could be considered to have lucked out. After all, since he had Mistress Annihilation's jade ring, he obtained Leader Hui Xin's acknowledgement. On top of that, his Comprehension was high enough for Leader Hui Xin to verbally teach him Emei Sect's Divine Yang Skill.
"Learned Emei Sect's Divine Yang Skill!"
[Emei Sect's Divine Yang Skill.
[One part of Nine Yang Divine Skill. It is a qi cultivation technique that provides qi of the highest purity and greatest degree. However, the incomplete Nine Yang Skill will only increase qi recovery speed as well as your resistance toward soft palm strikes.