My personal feelings on what axel is for is that he is one of thoes dudes who does whats right. (or what he thinks is right) So he is trying to help the Kh Universe (what ever you want to call it) by doing things that he thinks is good when actually is is Evil, but he doesn't realise it. Then after a very (i wanna say) Emotional? battel with sora he "see's the light' and relizes what he has been doing was more bad then good, so he sets out to fix it, and in his atempt he dies dramaticly. (like whats his face in FF 7) *OMG! slaps himself repetedly for not remembering the guys name* but anyway that is just my personal thoughts on Axel.
(does that make any sence?)