Regarding melee i think they should get rid of the current animations and add mine:)
Since guardians utilize the travelers light i thought guardians could put it into their panic attacks.
Regarding Titans: I think they should have twin light tails to wrap around an enemy and crush them in fast constrictor style. (Tails should be long to counter warlock melee range)
Regarding Warlocks: A third light arm should protrude out of their right shoulder and do the same force push melee.
Regarding Hunters: Instead of the shanking style i thought that a light dagger should materialize out of the left wrist. The hunter would then stab at the chest region.
Regarding customization: Default colors would correspond to each subclass I.e. Defender Titan=purple twin tails. But When you have lvld to 15 you may purchase from the speaker unique colors as well as effects.
Hope you like my ideas!!