Essentially with a blind spot you can't ever get better with that kind of magic (you can cast it, you just aren't particularly good with it), but you get an extra free specialization in another form. So Harry might have a blind spot for veils, but a double specialization in fire, right out the gate.
Harry compensates for his lack of fine control with foci, like the blasting rod for precise applications of fire. How does that work in the game? If Harry has a blind spot in control, does the staff partly or fully cancel the blind spot? If so, what's the downside to the rod (besides that fact that it can be lost or stolen, of course)?
Dang, I cannot WAIT for this game to come out!