More brainstorming:

What about a Fleet Support upgrade along the lines of:

"When a friendly ship is attacking a squadron at distance 1-5, each of its [critical] icons add 1 to the damage total."

or

"When a friendly ship is attacking a squadron at distance 1-5, each of its [critical] icons add 2 to the damage total."

or

"When a friendly ship is attacking a squadron at distance 1-5, it may reroll 1 die."

You could reduce the distance/area of the effect in order to keep the cost manageable (especially on the second one).

I like this, but I'm a little unclear on your intent. Should it be "when a friendly ship is attacking a squadron at distance 1-5 of this ship" or should I read it, as written, a squadron within 1-5 of the attacking ship?

I might also want to extend it to squadrons. Call the upgrade "flack guns" and since it's fleet support, it's limited to flotillas (currently) which somewhat limits it's usefulness. OTOH, I can see a wing of Gozantis all equipped with this plowing directly into an enemy fighter formation. Could be glorious.