Yeah, he had a small portion of it. He had years upon years to master using that power and then Thanos came along and pwnt him after only having the power for what, a few pages?
time is relative [especially when a being can mold it like silly putty.] thus, what appeared to be a few pages to us readers could have been eons to thanos - though i do believe he mentioned some sort of period/time frame in which he adjusted to teh powa. *shrugs*
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anyhow, akhenaton was merely a conduit in which a portion of THOTI's energies were channeled through. thanos, on the other hand, was THOTI - and from what we saw on panel, that's what it took to defeat LT.
LT ftw.
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"I am tired of Earth. These people.
I am tired of being caught in the tangle of their lives."
LT wins this. Thanos was able to take the HOTI and defeat Akhenaten at his normal levels. Even with the IG, Thanos still couldn't hope to defeat the LT.
If LT went rogue and attempted to take the HOTI for himself, even just a part of it as Akhenaten did, then Thanos wouldn't have been able to pull off what he did. LT could've sent him to Oblivion.