[Mewni]

If you want to be a Duelist x Something and relies on on-hit [Why majority gets it anyway, because of Fleur]. There is nothing else to go towards but Ghost really, the other classes are not a bonus to your setup, but a class you should focus on, Firebird and Kensei is not something you take as an 'extra' to help your main thing. Ghost is versatile and easy to fit in any class, so thats why its being popular.

Not because its the best thing in the world, but because as a duelist it's the only thing you can take if you don't want to focus in a class promo you are picking to support your main thing.

It's simple really, takes the whole of two minutes in thinking to actually get into that conclusion.

Also, about 'RP aspect' Dev already said that classes does not define how you RP or play said class, so no, there is no right way to play ghost, because you can flavor it however you'd like, seeing someone go "Oh! a fellow black knight!" to someone is the cringiest thing possible.