Does the Bianchi Axis have rack eyelets. From the website it appears that it does have upper eyelets and probably lower ones that are plugged. If you have eyets you can fit any std rack which is lighter, stiffer and stronger than a clamp-on style rack.
Get one with good triangulation, 3 legs, a rear lamp bracket. I prefer non-adjustable height and get the correct size to start with. If you panniers have good stiffeneing then you dont need the dogleg style. I prefer the top of the rack to be an open frame rather than top-plate so lashing larger loads is easy. I would also avoid proprietry rack fittings such as Topeak.
Black panniers show wear much more than silver ones.