Man, she is a piece of work! He asked her to tell nobody and she blabbed to LITERALLY the first person she met...
Pretty sure that was the point. She can't tell anyone
within the country so as to not interfere with local business, hence him asking her to leave immediately after her purchase
. Outside is a completely different matter.
The good knives get taken out of circulation from that country and the cheap fakes keep flowing in. He gets to sell his work more reliably and the merchants get some excellent product to resell (presumably at a crazy high markup since it seems he sells his stuff cheap). She's doing him a favor as thanks.
Or, if you're more cynically minded, she's making some extra dough while throwing him under the bus since she's already agreed to leave the country and basically won't be able to be tracked down. She has been shown to be quite ruthless before (Chapter 11 springs to mind) — this would comparatively be rather tame. I like to think it's the former though, or at least a mix of the two.