I have a gargantuan amount to say on this topic (and several others that intertwine with it), which I'm still working on compiling into something intelligble. That being said, I will drop a suggestion here in regards to Mimara's Judgement vs The God's Judgement, which is:
What's the difference?
Put it another way: Mimara is the ring-bearer -- er, I mean she has the Judging Eye not so much because there's something special about Mimara herself exactly, but because Mimara perpetrates the Will of the God simply by being Mimara. Is someone damned because Mimara thinks they are? Yes and no. The same goes for so-called redemption -- though I think a better word might be Absolution, for that is what she (and/or the God) truly offers. An invitation to join the Absolute -- which itself is one and the same with Oblivion.
Likewise, I think this way of thinking can be applied equally to Kellhus. For all his Dunyain and sorcerous abilities -- which are mighty indeed -- he is still, ultimately, "just a man" (in one of his POV's in TGO he even describes how Men see him, with "two hands and one intellect" in reference to his halos, which is also perhaps the first real revelatory glimpse at the meaning/nature of his ever-mysterious halos themselves). Kellhus's will and actions are indistinguishable from the will and actions of the God Itself, though neither Kellhus nor Mimara need be fully aware of this fact.
It is, perhaps, no coincidence that the only characters we see bearing such halos are Kellhus and Mimara.