Astarion was a slave and a dress up doll for his vampire living in a fancy mansion, then was snatched in the middle of it all by the mindflayer. He should be drenched in fluid, but he should not have had chance to change into suitable traveler wear, that's on you to do, Shadowheart's deal might be more similiar to Astarion then we currently know in that regard. I agree on all the Tielings going on about how they aren't soldiers and don't stand a chance in a fight but all are dressed in the fanciest armor in the game is silly.