When used as a subclass the Luster's main mechanics that carry over is the whole Voltage system. This means you can play Hunter/Luster if you would like a bigger focus on damage provided you can reach maximum voltage (500 Voltage) as I recall the Luster provides very high damage compared to other class combinations but the main problem is maintaining voltage because any period of five seconds where you are not dealing damage (including cutscenes) will completely reset your voltage. For some classes like the Bouncer this can be a godsend because the Dual Blades/Soaring Blades with their technique-cancel trick (hold a technique on the subpalette and then spam the weapon action button to shoot Photon Blades and skip any "delays" in the animation) alongside Photon Blade Fever can be infinitely sustained (or have a non-existent cooldown) due to how Voltage works.
As a Gunslash user all classes have "normalized" Gunslash damage so it will now be a viable weapon with a Luster subclass but some class combinations make this questionable (Force/Luster and Summoner/Luster, for example, who have very little need of a melee/ranged weapon outside of PP Batteries or classes like Gunner who excel more with the Twin Machineguns than a Gunslash).
Beyond that, the main-class Luster will exclusively focus on their Gunslash and the element of the Gunslash so you typically want three of them built for different elements or at least two at minimum. You can take the Soaring Blades S4 and use that with an elemental ring (I cannot recall the name of the S4 as it was "S4: Genesis Ring" in the fan-translation) which allows you to equip status-rings like "Burn Ring" or "Panic Ring" to switch elements on the weapon. While all three weapons play very similarly (even more than the Hero's three weapons) each style has their nuances that you want to take into account in order to build the Cluster and to maximize the style's capabilities.