SpoilerSorry for not posting - I was DMing a real life game!
Androse takes the mirror - examining it himself, searching every angle, trying to see if it had some magic to reveal the true self of those exposed to it.
He wasn't sure why he felt that's what the mirror did - in fact he never heard of such a thing, but it just seemed the right place at the right time.
"Unusually heavy, yes," he agreed, trying to search the eyes of the merchant. Something was up. His dragon-sense was tingling.
The dragon spoke firmly, glancing up to the man, stepping forward toward him: "Say, where exactly do you come from? We are travelers from a faraway place, and I reckon you are as well."
Spoiler
Specific knowledge he is using:
Knowledge (the Planes): (1d20+15)[29]
Knowledge (Arcana): (1d20+15)[18]
Knowledge (Religion): (1d20+15)[18]
He is looking at the object to try to determine what plane it might be on, any magical abilities a heavy mirror might have, and if it has religious significance.