Saix once said: "The rage of the keyblade releases those hearts."
The organization was using Sora to gather hearts for Kingdom Hearts. Does that mean only the keyblade can release hearts. If that is so, then how come when any other party member slays a heartless, it also releases a heart?
I'm noit entirely sure why but it is true, This was why Roxas was so overly important to him, They called him the Key of Destiny for that very reason...
True. Yet think Sora wasn't always angry or in rage but maybe the keyblade I don't know. Yet I think it means that since Saix hated the power of light he called it rage. So light purifies dark making it go away and thus may seem like a banishment for the dark. Saix may have seen things the other way. Dark was good for him and Light was evil. Sora was trying to get rid of the dark and looked at it like it was bad. So thus, the phras comes into play. When Sora uses the keyblade it gets rid of the darkness to release to heart and thus making the dark banish from it.
I do kind of agree with this, I think yes the keyblade slayes the darkness the not heart... I think this be the case because like MX said "A heart overtaken by darkness cannot weild the keyblade." Which means the keyblade is a weapon of light. So I believe the keyblade takes the darkness out of ones heart, (I'm talking KK here).
My other thought is kind of what the org wanted to do... And that is they wanted to trouble Sora and confuse him, In turn they did... I'm rembering the clip from final Mix how Saiix is talking to Xemnas...
Saix: I told Sora. I told him to keep defeating the heartless.
Xemnas: Well done. You did not just hurt him, but also threw his heart into confusion. Yes, This will gain us many hearts. Now Sora is confused and hesitant. In the depths of confusion he will begin to even hate himself... And in attempt to shake off the confusion, he will continue on more determined than before.
I really think it's both these reasons tied in together. So yes to sum up what I've said the keyblade slayes the darkness then the heart goes to KH which is what the org wants. Cause as Sora said "Kingdom Hearts is light"