I doubt that particular word (katana) would be quite so permanently stuck in my head if not for watching Teenage Mutant Ninja Turtles a lot as a kid. That was a show that was for-sure aimed at boys.

The other places I could imagine having encountered it enough for it to have stuck are action video games and Japanese or Japanese-influenced action cinema & anime. I have some very confident guesses at how male and female interest rates in those would break down.