considering she said he went from dagger to greatsword, i’m assuming he was turned on at the prospect of getting some special ore to forge with. Now that’s a blacksmiths boner i tell ya what!
@lenovoaxioo - on the last page, appraiser looks at MC with her pervert-vision, and says "a greatsword" and gulping. Compared to saying "hello there, dagger-chan" at her first appraisal on page 4.
We're pretty sure she isn't talking about Imperials, she is talking about MC's penis. Because we're so perverted.
So all childhood friend-chan has to do is cosplay as some rare ore for sword making and that way she'll get laid by Tatara after some blacksmithing forplay and then he can bang her just like he bangs his swords with his hammer.
You see, it's not that difficult once you know what he likes. Just gotta be creative a little.