When did he read the 9 yin manual? There are two sets of events that need to be reconciled here.
From LOCH:
WCY obtains 9 yin manual.
Huashan tournament to determine possession of manual.
Exhausted from the tournament, WCY passes on XTG in exchange for 1YZ.
WCY dies around a year after the tournament.
From ROCH:
WCY enters Ancient Tomb and finds counter to his skills.
WCY reads 9 yin manual and finds counter to Ancient Tomb skills, and inscribes these 9 yin skills in secret chamber.
WCY dies, admitting he didn't use his own skills to counter LCY's.
At some point, WCY read the manual and absorbed its essence, and inscribed the skills on the walls in the Ancient Tomb. Yet he died not long after the Huashan tournament. In the 3rd edition (IIRC), it's only after contemplation that he admitted that he didn't after all best LCY with his own skills.
So did WCY do all that stuff involving 9 yin and the Ancient Tomb in the year or so after Huashan, plus all that stuff in Dali? Or did he read it and absorb its essence before Huashan? If the latter, would his clear victory be less impressive considering he had the benefit of 9 yin, unlike the other four contestants?