REGISTER TO REMOVE ADS
You're half right. It took place in his mind (as he has his Org cloak like in the Twilight Thorne battle [the cloaked version appears a second before the TT]) as Roxas' was struggling for control after Axel's death awoke him.Nahh.. it was just a fight in sora's mind, and the purpose was roxas wanting to make sure sora was good enough for him to give up his existence.
I support this theory
Oblivine represents Sora's memory(and what not) for Riku
Oathkeeper represents Sora's memory(and what not) for Kairi
No real proof, or anything to back this. It's just kind of a guess.