@Deadset that Eternal Full Eclipse isn’t a Cheat. that is what happens when you make a Mythic Affix on an Eternal Mythitech Item. three of the Sockets with Myth Stones disappear, and you can then place Epic Affixes on them, just like with the Eternalized Items. I looked at another Post about this, and a Snapshot shows 1 empty Socket. so when you put a Mythic Affix on an Eternal Mythitech Item, only the Set and Legend Affix are left, and one empty Socket. so you lose 4 Myth Stones and gain 1 Empty Socket and 3 empty spaces for Epic Affixes.
also, only Eternal Eternalized Items can have a Mythic Affix, which is how the Eternal Mythitech Items can have 3 Epic Affixes and 1 Myth Stone.
here is the Post I was looking at… it also has a link to the Post explaining that this is the Developers intention.