Wei Wuxian knows all about swords that have a turbulent spiritual connection to their masters. And also ones that can be dangerous to their owners after awhile. All one has to do is look at the history of the Nie sect. If he senses the different emotions during the pass off he doesn't mention it. No reason to question the man's connection to his spiritual weapon. Not when Wei Wuxian has his own issues in the past.

"I'm just glad I was able to keep it safe until you could be reunited. It was just luck that I happened upon it."

Not that Wei Wuxian feels like he has a lot of luck on his side most days. But it is clearly meant to be that he encounters another cultivator on this day. "These worlds can take things away or give things back in the strangest of ways. It's no fault of yours that you got separated."

His own sword was reunited with him on the other world through odd methods. Sometimes items from their worlds just randomly show up, or are given in payment of a good deed. He hasn't quite figured it all out yet but he has obtained a few items from home over his time away from it.