The levels on my Ronia are lower, sure (it's a work in progress), but it shouldn't have THAT much of a big difference:
Ronia team:
Ronia - Max
DMeta - Max
Lu Bu - 50
Haku - 60
Vampire - 49
Vampire will probably be replaced with Persephone at some point; DMeta replaced with D/R Luci (though I'm on the fence on that, DMeta's extra skill boost and damage reduction, as well as raw stats are great)
Athena Team:
Athena - Max
Verche - 68
Apollo - 79
Izanagi - Max
Odin - Max
The damage should be at least somewhat comparable since they both run at 9x atk (Ronia at 6combo is at least), but it's not. I know TPAs make a huge difference but I just don't get how people wreck shit with Ronia when I consistently fail to do so.
I think the difference between the two is Athena is not really meant to take many hits due to her nonexistent RCV stat and no RCV multiplier on her LS. RSonia, meanwhile, has pretty good HP with the right subs(she herself has a pretty high score for someone with ~1850 Atk) and her RCV boost being so high means she can recover it all really quickly outside of No-RCV dungeons(In which case you'll either use another team or use the extra skyfalls to generate more ammo that much faster I believe?)
It's the opposite for me. Athena teams have low RCV by default, yes, but my setup has monstrous HP (over 31k with a +297 Athena friend) and the low RCV is supplemented by Odin.
Meanwhile, my Ronia team just can't take a goddamn hit. It can recover from near-death easily, but that means nothing when multiple things kill you at once because the damage just isn't fucking enough to take them out.