Nope but I'll copy and paste what I posted in that thread cause I'm lazy.
I'll take a stab at it.
Simple and to the point, the transition of the Seventh Umbral to the Seventh Astral.
Even a catastrophe, such as the Seventh Umbral, could not stop the true nature of man. Greed, war and power still drive the animalistic natures of man whether they be Garlean or Eorzean. Selfish desires will persist even through the hard times.
The Eorzean Alliance and the Garlean Empire are the 2 'swords.' The blade born of light doesn't refer to light vs dark or good vs evil, both of those are subjective as everyone views their own ideals as good and opposite views as being evil. Instead the blade born of light means the Eorzean Alliance and the Eorzean people have opened their eyes and realized the threats that have surrounded them, whether it's the Garleans, Primals, Ascians, traitors in their own ranks, or hidden dangers not yet seen.
The blade forged of might is clearly the Empire under Solus zos Galvus, he rose to power and made the Empire what it is today with his intellect and machina. In contrast with the sword of light, he created the blade, while the Eorzean Alliance was (re)born.
This line doesn't mean much to us as we don't really have much of a choice in that we're adventurers fighting for our Grand Companies and not given the choice to aid the Empire. But story wise, the people of Eorzea could choose to help the Alliance or rollover and allow the Empire, who without van Darnus would probably be more than happy to accept the people into the ranks with a little brainwashing here and there, to do their thing and takeover and destroy the Primals or whatever the true goal is. But the line dictates there is no middle ground, it's one choice or the other. The Seventh Astral depends on this line and the choice that is made.