This might be an idea.
Evolved class.
If you have mastered a class then you can evolve/upgrade it. This is something by earn.
An evolved class is buffing up your class.
Shock
Your tech get upgraded and you get a Shock rocket which stuns and damages your enemy badly, the E.M.P which is like an aggrobomb but stuns the enemies however, due to its power it cools down twice as slow. Shock Zone, you create a field where any enemies that approach to the zone gets stunned instantly and finally An armored attacking aggrobeacon, more armor and has blasters that attacks the enemy.
Storm
The rocket launcher turns into a Warhead, you shoot it except it stays still for a second and then charges at the enemy dealing twice the damage, Instead of an aim computer you have a blaster rage (bonus it doesn't make you miss your hits), it buffs up your blasters and makes you shoot like the anti-mantis turret does for a period of time. You deal twice the damage for a period of time. Instead of a perforator, you have a double shot, it makes you target 2 enemies at a time and last but not least, the flame zone instead of the thermoblast, a field is on fire and any enemies that enter the zone slowey loses its health.
Tank
The Tank buff increases the armor by a lot however, instead of the shield, you have an advanced shield with a faster cooldown and instead of a taunt you get a mega taunt, you taunt multiple enemies, instead of an aim scrambler you have a deflector shield which makes blasters, rockets (except sniper blasters) be deflected and hit the enemies instead and last but not least the heavy aggrobomb, like the aggrobomb except you deal twice the damage except the cooldown is still the same unlike the strong aggrobomb.
Engineer
Instead of a repair target, you get a multiple repair target which makes you repair more than 1 ally, you get a multiple protector which makes you protect multiple people (if just you then it's buffed), you get an advanced repair field which makes you repair twice as fast and last but not least, you get an improved resurrector, you ressurrect only 1 person except he is fully healed.
This can only be given to Lagrange ships due to the difficulties they will face in Lagrange and they're very very hard to earn.