Let's see how those cards work with the ships.
NK-7 Ion Cannons - 10 points - Blue Crit Effect: You may exhaust this card to force your opponent to chose and discard one of his defense tokens. Like most upgrades that rely on a critical effect, it works best on a ship with multiple dice of that color, not to mention a way to get regular critical effect rolls. It also works best against high hull and shield ships, that rely on multiple uses of their defense tokens to survive repeated shots.
For Imperials, the 4 Blue dice front battery of the ISD2 is probably the best platform, but it can work with really any platform if Screed or Vader tags along for the ride. Either ISD or the VSD can utilize it as part of a multiple turn shooting on a key enemy target. Raider IIs can be more of a hit and run plan in front of a larger attack.
For Rebels, the CR90B can do much the same thing as the Raider, but without really having a way to reroll dice without a Concentrate Fire token puts it at a disadvantage to the Imperials. The MC80 Command variant can do much the same as the VSD / ISD, but again without a way to reroll it doesn't have the best odds to get the crit effect off.
Overall, this is definitely an Imperial upgrade with the current Rebel limitations.
SW-7 Ion Batteries - 5 points - When attacking a ship, each of your unspent Blue accuracy icons add 1 damage to the damage total. This upgrade gives each blue dice a guaranteed damage against no matter what the roll - not a terrible thing at all. This is an excellent upgrade if your are running ships that are not expecting to prevent the opponent from using their tokens - after all, big ships can only brace once per round without wasting the token.
For the Imperials, the Raider II can guarantee 3 damage - not a terrible option for a flanker. A VSDII can also see some use out of this - but the best option would have to be on an ISDII with Avenger. Assuming you have other Ion Cannon ships using Overload Pulse - the Avenger is able to pour on the damage from its blue dice without worrying about defense tokens at all.
The Rebels have a use for this on the CR90B, giving automatic damage to the flanker and increasing expected damage from 2.25 to that guaranteed 3 (or 4 with a CF command). And for just a 44 point cost - same as a naked CR90A. Of the two MC80s, there is more opportunity to use this with the MC80 Command, and probably a better use of this with Ackbar. This gives the MC80 the option to use the Blue dice for straight damage, and also take advantage of any Red dice that get the 1/8 chance of a Red accuracy token if they actually need to cancel a token. For that matter, if Home One is also on the table they can guarantee a Red Accuracy on a blank dice and ensure the Blues are all actually damage. (Edited: To make this section clearer - thanks Drasnighta!)
And that is it for Ion Cannons in Wave 2. Only one thing left, and that is Turbolasers. Until next time, everyone!