An interesting concept for a card is the consolidation of attack dice. It could be something like:
[*I'm on the Leader] [Friendly ships within range 1 have the following action: "Action: assign a Leader token to another friendly ship within range 1, assign this ship a weapons disabled token". When attacking with a primary weapon this ship may roll one additional attack dice for each Leader token on this ship (limit 3). After resolving the attack remove all Leader tokens.] [5 points]
Obviously works better in swarms and mini swarms. It's costly, but allows you to convert weak shots into a larger shot that is more likely to punch through hard targets. At best you are looking at 7 dice, from 4 ships, so I'm not altogether worried about it being super overpowered (not to say it couldn't be tweaked somewhat). It offers some options for swarms to be able to compete with big fatties, but also probably helps 4 and 5 ship Rebels too.
Another idea is to allow Missiles and Torpedoes to fire in addition to primary weapons. Currently ordnance does too little damage relative to its cost (and opportunity cost, I.e. not firing that turn), so why not remove the opportunity cost? Let Ordnance fire either before or after a Primary weapon attack. Sure it pushes ordnance even further towards an alpha strike build, but when was the lost time you saw one of those? Stacking primary attacks on top of ordnance helps rectify the cannon/ordnance price inequality and makes them a serious consideration. It also in theory work against large fat ships who survive by reducing the number of incoming shots (I.e. Boosting) rather than pure damage prevention. Not sure it is a perfect solution, but it seems like a possibility given the bounds of the game we are working with.