Originally Posted by
ChanceEncounter
JY explicitly stated in his 100 questions that LHC's swordsmanship is better than YG's, in part because YG did not have a manual to learn from.
I think DG9J is more of a comprehensive sword philosophy than a simple list of stances. Neither FQY or LHC had mastered DG9J by the end of the novel. FQY didn't even understand the final, qi-breaking stance at all. I don't believe that DGQB would have completely ditched the philosophies of DG9J by the time he transitioned to the HIS or wooden/no sword stages.
As for LHC's potential. I believe DG9J is probably the highest tier of swordsmanship technique we've seen in JY's novels, maybe only rivaled by 6MSJ. Though I think of 6MSJ as more of a kind of qi-sword that acts as hardware, where DG9J is more of the technique/software, which would technically make the two compatible.
YJJ is at least on the level of QZ internal/9Yin/9Yang. Some narratives may place it above them, but I don't think there's evidence enough in the books to rank it higher. So upper bound is great level internal and superior technique, which makes him more than a match for XF/GJ/YG/ZWJ tier of fighter.