With the forthcoming 'potential' changes to the skill tree, and the 'potential' for all of the weapon-types to become viable, at least from a skillpoint investment standpoint, there seem to be two paths that the Devs could go in differentiating weapon types. Either give each weapon a meaningful proc, or go to a completely static differentiation.
Phaser: Keep random subsystem disables, but drop Shields from the possible systems (if Viral Matrix cannot drop the Shields, why should Phasers be able to do so?); change to an alternate type of proc?
Disruptor: Proc provides a hull resistance debuff, helps self- and team-applied damage to target's hull
Tetryon: Change shield stripping proc to a shield damage reduction debuff, working in a fashion identical to the Disruptor proc, only against shields, rather than hull.
Plasma: Proc provides a Hull DoT, which also slows the target.
Polaron: Buff power drain effect to be persistent for 5-8 seconds, then returns, as normal, based on the target's power regeneration rate.
Antiproton: Give AP weapons an 'actual' proc?
By differentiating via proc, weapons are essentially identical, with a fractional difference, suited to taste. Ultimately, this becomes likely easier to balance (long-term), as the low proc chance renders limited differences between the weapon-types, and players can choose their weapon preference based on things like canon or aesthetics.
Phaser:+10% inherent Accuracy.
Disruptor: +10% damage against Hull (at all times, does not apply to bleedthrough?).
Tetryon: +10% damage against Shields (at all times).
Plasma: +10-20% bleedthrough damage?
Polaron: +2% Critical Chance?
Antiproton: +20% Critical Severity
By differentiating via static means, weapon selection actually becomes a meaningful choice. Allows tuning of builds to complement weapon choice, but might slightly detract from builds centered on either 'canon' or aesthetics.
In either case, the 'fix' to make all the weapon-types cost the same, in terms of skillpoints invested, will allow for much greater variety and flexibility in weapon choice, but some consideration would need to be given to valid differentiation between the weapon-types.
All I have to say is hello tetryon stackers tho. It's muh fav, but maybe the stuff shouldn't stack. Idunno, dirsuptor works that way now but..... After reading that post tetryon would be my clear new best choice.
Also the plasma weapons slowing target is great. And I like keeping the antiproton with heavy crits as a bonus. No other proc needed there I don't think.