Yeah my brain rotted out from a decade + of isekais where they always glaze katanas. I'm just tired of them, there are dozens of other things you could be using. Shamshirs, Longswords, Jians and that's just swords. How about Halberds, Maces, Poleaxes, Axes.
Well, then you'll probably be happy to know that in the newest chapter (ch. 44), Mizuha said that at her dojo in Vistcourt, they don't need the forging technique for the katana and that even some of the students wants to move away from the single-edged style, since their style is more focused on fighting monsters rather than duels. And Aesir said that he wants to take the two different style, reunite them and make something entirely new sometime in the future. (Assuming you haven't already read that chapter yet)
And not to mention, the sword that Aesir still uses is not a katana.
I was rereading another chapter, and Aesir said that he liked the food from Nonna's inn even more than the soba noodles from that Japan-like country. I believe that what the author wants to show is that the old Japanese stuff is nostalgic and great, but new stuff can be just as good or better, and mixing new and old stuff would be even better.