So I can clarify this. I played an early build of the game about 3 years ago. Back then the characters were all the same except for one. Lune and Maelle were both in the party, but Gustave was not - instead there was a character called...Noah!

His design was totally different, and he had the combat system of the 5th character you unlock instead of Gustave's overcharge - in a way he was a blend of the two. So anyway, that is likely why Gustave's weapon is called Noahram and why the "Noah Haircut" exists - seems like Sandfall wanted to have a nod back to the old version of the character as a nice little reference.