A new thought on what Vita’s plans in Sen II could have been.
Let’s start with what we know. The original Sept-Terrions of Fire and Earth beat each other up until they fused together leaving behind their original bodies and becoming the Great Power, Steel. The bodies that were left behind became the Curse. Essentially, the Sept-Terrions fused and then separated in Power and Curse instead of Fire and Earth.
We know that the Holy Beast of Earth absorbed a portion of the curse turning it into the Nameless One. Here I propose that something similar happened to fire, but instead of being cursed it absorbed power. The Holy Beasts became the Holy Beasts of Power and Curse.
We know that Gnome’s plan involved killing the Nameless One to fully unleash the curse upon the land of Erebonia and that it will eventually lead to reformation of the original Septs. Since the curse is their bodies, its obvious why they have to unleash the curse to reform their bodies, but now they need to concentrate it in a single location. This is where the war with Calvard comes in. By focusing the anger brought forth by the curse on a single spot they can concentrate the curse at that spot, that spot being Crossbell.
Now that they have the body, they just need Steel, but Steel is in seven fragments encased in a Zemurian Ore shell. This is where they need the Holy Beast of Steel which is the only entity capable of destroying a Divine Knight. In fact, that was Vita’s original plan when she summoned the Demon Castle. She and Ouroboros were perfectly fine with just acquiring Steel and ignoring the curse. However, for some reason, the ritual failed to summon the Holy Beast, and now we have to deal with the much more destructive gnome plan.