Not sure I get what you meant with the lines following your REMEA comment, Fae.
Not saying I don't agree, I just an not sure what you meant.
Relic is one category.
Empyrean is another (bound to different content, different jobs, different aftermath)
Mythic is the third category.
Ergon have a different name and a different way to obtain them but they are de facto Mythic weapons. Same Job specific approach, same aftermath etc.
It's quite simple... Or at least it is when you understand that mechanically poorer version of X does not mean that it's weaker/worse than X.
It's all design not function/application.
Empyrean weapons were added to the game to give ToAU+WotG jobs access to relic weapons. (Obvs PLD and BRD came out better than everyone else. But that was a side effect, not the intent.)
And what are these weapons? High-damage-low-delay weapons that can occasionally deal 2x dmg (that's up from when it was just 2x back then).
Weaponskills are irrelevant here, since I'm just talking about the weapons themselves. But it's obvious to anyone with a brain that the empyrean WSs have always been vastly superior to their relic counterparts.
But their aftermath is where the equivalency, in SE's eyes, is made.
With AM up, an empyrean is the same as a relic... But we know that AM is a fragile thing. So, mechanically, empyrean weapons are inferior copies of relic weapons, who have the ODD naturally.
This is ESPECIALLY obvious when you look at their damage and delay: for almost all their lives, relics and empyreans have had identical delay and damage. For the most part.
And Ergons are Empyrean!Mythics.
Much like empyreans they lack the same-WS-dmg-multiplier. And much like empyrean and relic WSs they have LIGHT and DARKNESS SC properties, which Mythics never had access to. This is because they're supposed to not only be RUN and GEO's mythic but also their replacement for lack of Empyrean WS. (Always a big fail that GEO didn't get "Mystic Boon2"...)
Ergons only real link, aside from a massive time investment, to Mythics is that they share the mythic aftermath. (Being JSE don't mean anything, just look at any of the JSE relics or empyreans.)
So in essence: Empyreans came to be to be the relics of ToAU and WotG jobs, and Ergons came to be the Mythics (and empyreans) of SoA jobs.
And both are mechanically weaker than the weapons they're emulations of.
Though, obviously to anyone with half a brain, mechanically weaker doesn't mean intrinsically/functionally weaker.
(Though in 119 terms empyreans are literally the weakest 119s available... That's a new thing.)
And it doesn't mean that they're bad either.
It just means that SE was being lazy (because adding jobs to something is literally the easiest thing to do in a video game) and instead of updating old weapons they just made new ones.
Which just always benefitted the old jobs more. (And why I'm massively against Ergon for all.)
Which is why these Aeonics will be interesting.
They're not really fake!mythics (like ergons), and they're likely not fake!relics (like empyreans)... So... There's no need for them.
Which means there is no forced design with them!
(Eg: high-damage-low-delay, LIGHT/DARK SC property, specific AM, etc)
They can literally be anything!
And that's exciting.