I watched the scenes again. The alteration of the speaker's voice, from one which sounds like Arbert's, to a booming one, is ostensible. Still, could it be the result of mere distortions?
Though the "eon become instant" line is suggestive of time compression, what if he is simply saying we need to bring things forward... faster? The "History must be changed" line does point to time travel... BUT - what if it is not the past in the strict sense but the trajectory we're on? This could make sense if the person speaking is doing so with a vision into the future in mind. What I have in mind is that not only is Zodiark able to manipulate time but also sees it as a compressed singularity.
Another possibility that crossed my mind is that some of his words may have been lost during transmission, e.g. as with the "That way... sorrow" part. So we might not be getting the full picture.
I'm also not convinced that the "we" part is decisive, even with the knowledge that Zodiark is a deity and adept in such practices as soul merger. It might be intended, though, to create the ruse that it is the Warriors of Darkness.
It's probably the part of the lore I am now most eager to find out more about. I had always thought Zodiark was dormant and unable to perform such acts - maybe he has regained enough power to do so? Or is it Arbert acting at his or Elidibus's behest? Arbert's conviction was certainly very strong, and here is a reminder of the outcome of that storyline. with his parting words of wisdom:
https://www.youtube.com/watch?v=SMMr_BZddAw