well Adel....I don't know if your still active here on the forums or not but let me clarify one thing....even if it is a month later....
In order for your aeons in FFX to deal more that 9999, you have to unlock the power of the final weapons for you party members. aside from Bahamut. Something that's pretty common knowledge but just incase you didn't ever figure it out somewhere else, I put it here for you, as well as for everyone else that wasn't aware of it......