I like the Integrated Weapon rule from Bell of Lost Souls. It reads as follows:
Integrated Weapon: The Ordinatus is literally built around its main weapon and is more an extension of it than a simple vehicle which carries it. Any weapon listed as an Integrated Weapon is only destroyed upon the destruction of the Ordinatus and is immune to gun-crew shaken critical results.
I propose making this a vehicle upgrade available for others to use, to apply only to Primary Weapons on those vehicles that look like they should warrant it.
Requirements: Applied to one Primary Weapon on a Super Heavy vehicle as long as there are no other Primary Weapons or Ordinance Weapons on the vehicle. Cost: +50% of the vehicle's total point value.
My original version, Damage Control Shunts, gave you the same immunity but required you to pay a structure point every turn when you wanted to use the weapon. It certainly would have been cheaper in terms of points.
As you can see, I am not afraid to pay for what I want. I'd prefer it if we figured out a graceful way to give it to Cobras and Shadowswords but not Scorpions or Baneblades, but I can't really come up with one besides just making a list. Making a list just calls out for exceptions...
What do you think?