The Dark Divinity 3.0

[Ibi]

The problem is that they are fairly nondescript. All Primals are powerful. Leviathan could summon tsunami's that could wipe out Limsa, for example. If we're assuming that the Eikons are, somehow, more powerful than your average summon, than, at most, we're talking about Elder-Primals.

In this interview, Fern said that the difference between a Primal and an Elder Primal is "a matter of length of worship", rather than any measure of how powerful the Primal is. Elder Primals are not intrinsically more or less powerful than Primals.

We've not see the Warring Triad in action (nor do we know in what way the massive statues of them are related, in scale, to the eikons themselves), though we do know (from the Extreme Primal quests) that Ravana and Bismarck would have been eager to tap into their power. It's reasonable to assume, based on the quests, that the Triad are likely substantially more powerful than even the strongest Primals we've encountered so far.

The only entity we've interacted with that we've had confirmed to meet the Allagan definition of an eikon is Zantetsuken/Odin, who happens to also be referred to as an Elder Primal. That also doesn't really tell us how much of an overlap there is between those two terms. We do, however, know that Unukhalai doesn't bring up Bahamut Prime when he's talking about eikons, and Bahamut Prime is referred to as an Elder Primal.

My suspicion would be that all known Eikons would fit the definition of an Elder Primal, but the reverse may not necessarily be true. That is just my suspicion though. Either way, it's hard to infer too much about eikons based on the single data point we have.

Odin is the only odd Primal/eikon out in this regard, as, currently, we have no information about who summoned him or why.

We also know from T10 that Bahamut Prime required a massive amount of prayer to sustain his existence. We've had no obvious explanation of who or what is providing the source of belief/prayer for Zantetsuken/Odin, if indeed there is a source at all.