Since machinepistols, shotguns and all the laser weapons are nicely balanced in the first part of the game (before aliens have medium armor I used most of them) but become useless later on, I would suggest the following:
After the medium armor is researched, Phallanx realizes that some of its weapons have almost become useless.
Consequently they improve them... (new research options)
Just my ideas that sprang to my mind:
> new kinds of ammunition for the standard weapons specially designed to be armor piercing. One could for example use alien material to make the bullets (which would give "alien materials, 3 credits" some importance in the game) or rebuild the weapons with alien material, so that they can stand more stress.
> better energy source for the laser weapon => more power => more damage. Plus a good opportunity to make the heavy laser a bit stronger.
It's too weak compared against the machine gun in 25 round burst.
Just a few ideas that came to my mind after I read Destructavator's posting.
Andy