As the title says, but I have an idea to actualy give them their own weapons to use, rather than reusing already existing weapons and modifying their photon arts.
Make it like in the base PSO2: Quick, fast, maneuverable but lacks armor. Class main role would be curing status aliments inflicted by enemy and inflicting status alliments on enemies.
The new weapon I suggest for this class would a Scythe. The Scythe weapon is not the Rod, it will have It's own Photon arts, and can also use Techniques, primarily focus on close to medium combat. The weapon can parry, which will cure all status aliments on the player, and counter dodge which will able to initiate an counter attack that will inflict status aliment on enemy (Depending on the element used).
The second weapon of this class would be an Sniper rifle. Not to be confused with the Assault rifle for the Ranger class, this weapon would instead be more like the Assault rifle of the Phantom class in base PSO2. Default attack will fire single, very powerful shot, weapon specialisation would be summoning and controling small drones, and delivering slow, heavy blows from range. Good positioning should be they of mastery of this weapon. Can parry (Perfect parry only, just like the Twin Daggers).
Pretty much like in Base PSO2, heavy protection, healing passive and etc. Class role would be to provide defense/protection to teammates by giving them defensive boosts.
The class weapon would be an Axe. Primarily focused on close combat, can also parry while in the middle of a photon art, specialised on heavy blows up-close and personal. Can counterdodge for a stronger attack.
Saber sword. Not the sword that the Hunter uses or the Katana that the braver would use. The default attack would be quick and deal multiple hits. Specialises in manupulating gravity, creating small blackholes for Area damage or pull a group of enemies in single point and summoning small blads in air for ranged attacks. Guard stance would summon a bubble shield as long as you hold it (Only for a limited time though), just like in base PSO2, unloading all focus will create a powerfull attack. Counterdodge for a stronger attack.
NOTE: This is just my ideas, I'm not sure how SEGA would deliver those new classes, but I atleast hope they would return, but with their own weapons without making other classes obselete because they use the same weapons with altered abilites.