Now I know one of the Imperium’s maxims appears to be ‘There is no kill like overkill’ but I’m sure at some point in time someone has tried to put fake weaponry on a ship to make it appear more fearsome than it actually is. Perhaps a down on his luck Rogue Trader couldn’t afford the weapons systems so they decided to fake it or perhaps a greedy merchant decided to carve out more space in the ship’s hull for cargo by skimping on the weapons systems.

How would you stat such systems?

I’m thinking of reducing the power and space requirements by three quarters while still appearing on all but the most detailed scans to be the weapon systems they represent.

The other question I suppose is given the grimdark nature of the 40k universe and the tendency everything has to shoot first and ask questions never would an intimidating appearance ever actually dissuade a ship from attacking?

Not sure how you would start to stat that but it could work some of the time against single weak pirates. But it might also have the opposite effect in that a big well defended target must me carrying something of very high value to warrant that much protection.

My party has kinda done that, they went with a cruiser with "room to grow" as the Captain puts it as opposed to a fully kitted out Frigate.