I have a feeling this is kind of a larger question that needs to be answered. We know that this has to do with the Echo. We know now that the Ascians have the Echo too. This brings into question as to where this power comes from what it is capable of doing. The fact they say they have become one in the video shows they are using the power of the echo to join with the power of the figures on the floating continent who we know from past game lores (FF6 for instance) are figures who are all about balance. The Ascians are using their knowledge of the Echo to join with one of these figures to become the Warrior of Darkness. That is a lot of power for three beings to possess. The bigger question I am getting at is what is the Echo and why does it seem that even the bad guys (those we consider the bad guys) have it too?