This is all I know about Z'Thora. (I cannot say this is accurate AT ALL)

BEGINNING
At the start, all I know is that the sightless got HIM out of the void, probably referring to Z'Thora's soul and maybe the Z'Thora's Shell. After placing his soul into the shell(Stage 2),
Z'Thora's soul has awoken inside it. If switched to power "Soul-Strengthening Aura", the sightless asks "After what i did,Am i still worthy of this gift?", maybe referring to how they caused his soul to be there in the first place. Then Z'Thora goes on to pop them like a balloon, despite them asking for forgiveness. Also if you summon the artificial god when Z'Thora's shell is there, they will make it poof out of existence, after saying "Don't come back", and when their soul is there, the same thing happens.

STAGE 2 POWERS
Laser Beam:
-Shoots a beam that is like the future gun when something is around
Repulsive Field:
-Makes a field nothing can get past, kinda useless
Gravity Punches:
-Makes his punches stronger
Soul-Strengthening Aura:
-Strengthens the souls of his minions

SOUL STRENGTHENING AURA
this ability strengthens the souls of the gifted, but who are the gifted really? I think the gifted is the one's that he works with or chooses because out of all of them, he doesn't strengthen everyone he comes into contact with.

STAGE 3 HAPPENINGS
Stage 3 happens when the shell dies then the soul is put inside(maybe reviving the suit makes it more powerful?). After that, the shell glows brighter and his powers are stronger

STAGE 3 POWERS
Super Laser Beam:
-Shoots a beam that is like the future gun times 40 at anytime
Super Repulsive Field:
-Makes a field nothing can get past that hurts a lot, less useless
Super Gravity Punches:
-Makes his punches add G-Force to his victim, bursting that limb
Soul-Strengthening Aura:
-Strengthens the souls of his minions, still the same?(IT'S NOT IT)

RANKING
AAAAND hit ranking is...... low? Yeah, that's right, it's about a 7 which is very surprising since the shell has no clear ranking but, if you look at it, he's not that strong.
He is beaten by rank 6+ which adds a question why he is such a threat, but here is the reason why:
Soul-Strengthening Aura.
This power allows him to boost the power of other powered people, making them waaay more powerful than before, and can even activate other shells without losing his powers AT ALL, making him in the shell so dangerous but, he also doesn't seem to have these powers alone, I think he got them from the artificial god.(More on that in the backstory)

Conclusion
Z'Thora was maybe a human given powers by a god, then caused destruction by his minions

INACCURATE BACKSTORY
(Z'Thora's stage is STAGE 2 in this story, I am referring to PP's void)
Z'Thora was a normal person with a righteous heart and a hero. Chosen by the artificial god to become a powerful hero. After he received his powers, something inside him snapped, something dark, something EVIL. He went on to destroy his home town, giving some of them a part of his power, turning them evil also, with his true sidekick, the sightless. The artificial god saw this and sent hero's to stop him, but failed because he used most of powers giving it to Z'Thora, making all the new hero's weak. The god then gave the sightless back his memory, making them kinda good again. The sightless then gives away Z'Thora's location, making Z'Thora mad, then the god comes to stop him but can't because he still believes in Z'Thora giving Z'Thora the chance to strike but just before it happens, the sightless takes Z'Thora to the void, still believing in his lord. After that, the god sees that Z'Thora is a heartless, cruel being, assuming that his minions are too, betraying the sightless, sending them to the void(which they escape). Z'Thora now rest in the void, lying forever until the sightless saves his soul and his shell. They then return to the world and the sightless places his soul into the shell. Z'Thora is angry the sightless betrayed him, being his sidekick and his only trustworthy partner. He erases his partner from existence, now on his way to get his revenge against the god.

EXTRA NOTES
Please know that this only covers a bit of the story behind it, I am still figuring it out with the help of the other posts and discussions and from "figuring out Z'Thora and the sightless" provides extra information and from it's comments and it also covers more things like Z'Thora's level(which i think is kinda underestimating him).

The backstory is just me guessing how it went down.


UPDATES
Update 1.1:
-Fixed inaccurate stage information(In backstory)

CREDITS
Please post in the comments leaving more information, this might not be fully true and may have inaccurate information or information missing, so please, help me out,
THANK YOU FOR READING!!!!