Even if I look at the specs on the slotted weapon, it's 412 versus 398, which is not a 12% difference one might expect.
For that matter... if the (3) consoles really boosted damage by 78% and 90%, the raw damage specs on the actual weapons should be 525 and 560, based on a 295 starting point.
Honestly, I don't really care if the weapon damage mechanics are such that what I see is what I should have expected. I'm just really mad I waste so much EC on a relatively worthless damage boost.
EDIT: you know the more I think about it, what I am seeing appears to be non linear stat adjustment, or something very similar to the way the captain skill trees work, where you get the most bang for your $$$ by 6-7 skill points.