A better question would be, who had the opportunity to learn those two martial arts? . We can't conclude, since he's the only person we know of who learned it. With regards to 6MSJ, the feeling I had was that he learned it 'easily' compared to others was because of his abundance of qi; in a similar way of looking at it, ZWJ was no martial arts genius, but he found it easy to learn QKDNY.Wrong. He is. Who else can learn Bei Ming Shen Gong (although just a bit) and Ling Bo Wei Bo in such a short period of time, same with 6MSJ ? Also, remember that when he learnt LBWB, he barely had any internal energy.
It's strongly implied though .He was, but it doesn't mean that the other monks were at the same level as him.
Dragon Balls Z!I don't think that's the case. It's more like Duan Yu subconciously understood the swords and how to use them, but he didn't have much knowledge of martial arts to keep his inner energy flow to wherever it's needed. Therefore when he's not excited enough , his inner energy flow would be stuck somewhere and the swords would not be formed.
The thing is, I really don't agree that DY had 'insanely' high amounts of qi. I think he had a lot, enough to place him amongst the very top ranks...but not near the level of XZ, who's simply a monster. Yes, he drained a lot of people...but how many of them really were of true worth? Sure, they were -called- 'first rate' fighters, but none of them were the true first rates. Basically, as I see it, he's overestimated.
Then again, I hate him, so my perspective there may be biased