Well, you'd use katana when talking about the specific Japanese sword referred to by that name in English. There's several different long, curved Japanese swords. XD

As for honorifics... yeah, I'll use them, but that's because there ARE a few that I've never seen a satisfactory alternative for that isn't looooooong character writing. It works, but does take rather an annoying time to become apparent. Especially in roleplays.