Yes the Tie defender couldn't cloak. In XWA they wern't god like, but good. I could easily take one out with an a-wing, but awings had sheilds and normal lasers . . .
In all the games i've seen it, the ion cannon was a blue laser that on impact had an electric fx (force lighning impact would be perfect) and in all of them (except rogue squadron) it took damaged a third stat called systems or similar which disabled the vessel: made it immobile, sheild and weaponless. (In rogue squad, being an atmospheric arcadey game, ionized ships just fell to the ground, simply a different impact effect)
Is there anyway to make a weapon that drains target endurace? I guess that would simulate it. Otherwise, just make em blue lasers with an electric impact effect.
(going off books here, not xwa)
XWA seems to have gone off the books too.