(...)
Again, that is why he needed the items, to become powerful again, to become a god again, so that no one can stop him. However, you prevent that. Ergo, no god-Manni. I don't know why people can't see and read the story-line in the quests. To become the god, he needed those items again.
Hear me, children. Once I was a lowly man such as yourselves. By my will I entered the ranks of the gods. By your unquestioning devotion, you can share my glory.
For soon we shall strike. The Temples of Arkay will be torn stone from stone. The blood of his priests will sate our thirst; their bones will rise as our servants. The name Arkay will be stuck from the records. Only I shall hold sway over life and death. Only one name shall be whispered in fear. The name of your lord and master.
KW - http://www.imperial-library.info/mwbooks/arkay_enemy.shtml
From this, it seems to me you are over complicating it. There is only one Manimacro. The King of Worms said he would became a god and return. Now we have a Necromancers moon that claims "He" will return. And what happened in Oblivion, Manimacro returned.
I'm not sure were you get the idea that he needs his artifacts to make him divine. Sure they might make him stronger, but he already seems to be a divine.
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The only thing arguing against divinity is that he went down so fast, but that's because Travens Soul was protecting you. Leaving nothing but an Altmer mage, with no armor, hardly any level offset. Without Traven, you just wouldn't have gotten close enough to hit him.