[ Rin is about to snipe back at Muramasa that that's exactly what she did, thanks, but she's interrupted by the client, which doesn't help her irritation with him. Her eyebrow twitches — at both of them, honestly — and her first comment is to Zelgadis: ] He's the only smith here — [ the second to Muramasa ] — you could try explaining it better, you know — [ and then back to Zel ] It's a barrier meant to keep out things that aren't human, or are otherwise cursed. For those types of people, they need permission or a charm to get through.