Esta is wearing +1 deathless studded leather armor. It's not 'go personally punch a Balor in the face' armor but that's not really his role. It's the sort of 4000gp armor you buy when you figure you ought to spend at least 4000 gp on armor, basically.
Without going into details of hardness, even the enchanted version is not quite as hard as steel. Powered tungsten carbide wins, if that's the sort of eldritch capability the Far Tapestry is going to bring to bear.
It is going to be mysteriously way harder to damage than the leather it looks like, but--