I think a full blown armor simulation would be easier than making up some "grades of armor" and implementing them on a case-by-case basis,
Idea:
*people wih good memory or keen sense of mantras already know what's coming*
My beloved Armor Treshold + Armor Resistance model from Fallout along with the multi type damage.
Implementation:
Serious table tweaking. + Modified damage code.
Example table enrty for a ship's amor:
- ------------Armor Treshold/Armor Resistance
- Laser---------------------30/15%
- Beam------------------- 120/7.5%
- Kinetic--------------------15/30%
- Explosive---------------- 30/45%
- Penetrating--------------12/12%
- Pressure/Area-----------20/85%
Whenever a hit occurs damage treshold is substracted from the damage, then the resistance*damage is subtracted.
Why the two values?
Imagine a function graph:
Treshold is just what it says - the armor can absorb and dilute this ammount of damage without any difficulty.
It sets the starting point of the graph.
Resistance is the steepness of the graph telling how adept the armor is at resisting that type of damage once it's treshold has been breached.
The types of damage should be weapon flags - all weapons should have at least one.
Most are obviously mutually exclusive (like laser/beam/kinetic), but when more than one are assigned the lowest value from the different stats are used.
For example an area affecting beam: GTVA implemented a beam system where fissioning materials are injected into the reactor plasma steam. As a result the beam emmits radiation all around itself, so being near one will also do some splash damage.
You can complicte that one by adding subsytem damage, but that should be more of a weapon's thing.