Ok, aside the fact that Ikki is miraculously still alive and drove Sora into a corner, apparently Sora had placed some kind of regailia into Rika (the storm regailia.... maybe?) and thanks to Ikki punching the other part of it in Soras hand, it's gone berserk and now is (most likely) killing Rika.
... or something like this. Do we really need to make it more complicated than it needs to be? Just let Ikki win and we're good. :)