Prescott would feel the blade was heavy - a bit heavier than his own iron one, though comparable in size.  The blade was surprisingly still sharp, its time away having long since sealed seeming to have little effect.  As for Izzy, she'd find the jar popping open after a bit of a struggle.  Peering down into the jar, the surface of what was inside was a strange, amber, crystallized formation.  Moving the jar around though would give the impression that some highly viscous fluid was inside - Izzy wouldn't be able to read the jar, so she wouldn't be able to know what it contained.

Izzy would also notice that in the dining room there was a pair of doors on the right - wooden and therefore likely fragile.

As for Valora, as she remained in the room she'd notice the dim light flickering slightly as something moved in it ... like as if someone was using their hands as puppets.  She'd see a dragon.  Then a bird of some sort.  Then it'd return to being the same, dull glow.