"A... Wei Wuxian who did not attack at Qiongqi Pass?"

He's hazarding a guess, considering what he's just learned. If this is Wei Wuxian, and he's managed to live sixteen additional years, and he hasn't attempted to lash out, then surely the disasters at Qiongqi Pass and at Nightless City had simply not come to pass.

It's what makes sense, anyway.

He's cautious regardless, face set in hard lines (but when isn't it?) as he looks the other man over, his evasiveness taking on new meaning.