I have been giving quite a bit of thought to how a B-wing might be more "unique" and of value to the game. The only remotely good idea I have come up with is an idea that originally came up when I was trying to stat out some Tie Defender miniatures I ordered from Shapeways.
I have come to call this mechanic the "integrated ion cannon" for lack of a better name. The essence of the mechanic is that you perform your primary weapon roll normally, and then if you scored at least one hit roll a die (or dice?) of some kind to determine whether any of the shots that hit were ion cannon shots. If this secondary roll is successful, the target ship receives one ion token (but does not take any additional damage).
Mediocre example text:
"After performing an attack roll that scores at least one uncancelled hit, roll one additional attack die. On a hit or critical hit icon, the target ship also recives one ion token."
Some various thoughts, of varying relevance:
-obviously the type/number of dice rolled to determine the effect is open to debate and tweaking
-should it be an innate ability of the ship type, or an equippable secondary weapon?
-If equippable, should it be a free or otherwise extremely cheap upgrade (basically just to allow more space for the weapon mechanic description on the upgrade card) or a costly upgrade like gunner/heavy laser cannon?
-it could also be a normal ship upgrade category with "B-Wing only" text to limit its use. This could also serve as a slight balancing tool if needed as it would prevent other ship upgrades from being used along with it.
-to balance the weapon, possibly limit the use of this ability to range 1-2 like the y-wing ion cannon
-possibly alter the number of dice rolled based on the number of hits. Less hits equals less opportunities for those hits to be ion hits
-if dice are based on number of hits, exclude critical hits. The way ion cannons work both in the game and in the fiction implies that a critical hit would never be an ion hit. This also means that critical hits against shielded targets would be of less value which could be considered another balancing mechanic of a sort.
-it could also have text for just using it as a standard ion cannon like the y-wing's (minus the 360 firing arc) so you could strategically choose between going for max damage with the possibility of an ion hit or limiting your damage to go for a guaranteed ion hit (assuming you hit in the first place)
Just some thoughts I had while theorizing the possibility of wave 3 ships and mechanics. Like I said this all came more from thinking about the Tie Defender and other possilbities for wave 3 so it's not especially well thought out in terms of the B-wing (or at all really)