Nazuna isn't even a flower knight, despite being named after a plant and having the cutest flower meaning in the game. You need the blessing of the worldflower for that and looks like she just isn't suited for it.

She can still outrun genuine knights (note that flower knights prefer not to ride to battle because they can already run as fast as a horse), move faster than the eye can see, and build an entire whale airship from blueprints she found scattered over the countryside. Definitely not a woman to be trifled with.