I forget if this was on this forum or not, but there was already a huge discussion on if Sora was a heartless a while back. It may have been the KHU forums... I'll write the gyst of it.Inner-Demon said:At first yes. But when Sora was recovered to his self, he became a Human Heartless. Roxas is his body and soul. Hence Roxas being a Nobody.
The Sora you play as after his brief moments as a heartless is only half of what he really is. When Kairi returned Sora to his state, she somehow managed to bring back his heart with his heartless. Since his nobody wasn't with the heartless at the time, Kairi did not have the abilty to reunite him fully. So Sora was only half if he really was. If he was a heartless, then he would have no heart. And a requirement to wield a keyblade is to have a heart (Roxas is an exception due to his original self), since the Sora's keyblade goes with the strongest heart (whether light or dark).