What is the point of having 3 variations for the Lunastra weapon?

https://preview.redd.it/ef3luzvazs9h1.png?width=1003&format=png&auto=webp&s=5d89bfc7fedf94c6a48d87a528d471c0fe7d435c

They even have similar stats, only differing slightly in dmg, affinity and sharpness.