I think it was also implied that had Shen Wei not weakened himself curing Zhao Yunlan's eyes, he might've been able to take down Ye Zun?

I'm not sure about that either. I think Ye Zun says that before, Shen Wei would have been a match for him, so perhaps they would have been evenly matched, but still not guaranteeing Shen Wei would win.

I agree Shen Wei should have told ZYL the two of them were brothers a lot earlier, although I wonder how much of Shen Wei's reticence in explaining the past was due to how much he knew about Kunlun being ZYL and concerns about messing up the timeline, as obviously ZYL had not yet gone back in time. I am still pondering that question of when Shen Wei realized ZYL was Kunlun and when he figured out exactly how the whole time travel thing had worked.