Isn't the stress in this game a condition of the pilot? (instead of the ship)If it stresses out the power of the interceptor then shouldn't you add gain a stress token.
So something like this. "When attacking if you do not have a stress, you can gain a stress to add 2 attack dice." Or something along that line. Could drop the points because of the stress. Would help lower PS interceptors being played.
I always saw it as a bit of both. Some things might be stress on pilot. Somethings might be stress on ship. But the Ion example isn't to bad. Of course with the Ion token the card probably wouldn't get used. Easier to remove stress then deal with the Ion. Just a thought anyways.