I don't necessarily agree that he was the weakest of the lot... I think that's putting it in too uncertain terms. I don't really think of him as weak so much as I think of him as trapped - and more than that, as angry. When you're raised by the military and you never get to do anything else, what are your options when they betray you? What can you really do with yourself when your entire life is a lie? I guess I can see what you mean by "weakness," but then it's hard to say whether or not he ever had the building blocks he needed to develop the strength to keep going and keep hope after a blow like that.

fftarot has a drabble on him under "The Magician" and it's probably one of the most interesting and thought-provoking pieces on his character that I've ever read.