Weston felt badly about the attack, as well, mainly because he'd been effective only as a herder of younger students. It was a noble task, to be sure, but given that the place had been under attack, he really wished that he could've done more.
And, of course, he was worried about his sister. It was his way; he didn't want to hover, but he hadn't really had a chance to talk to her in the aftermath, and he was concerned that she'd been hurt. So, after he'd taken care of his morning errands, he found his way to Pietra's room and lifted a hand to knock.