"Damn, those Rebel X-Wings keep beating us... let's copy their s-foils!"
Bit late commenting on this but there is actually a fighter like that, specifically designed to counter and be better than the X-wing, called the TIE Hunter. These fighters look very similar to them but the wings don't quite match up. Still could be the Hunter.
After going back and re-watching someone's playthrough of the old and great TIE Fighter game I have to say that the Missile Boat doesn't get enough love. The tiny little unassuming ship that zips in fast and kills everything.