I feel so-so about this.


Your proposed change for this minimal damage decrease is either going to be absolutely pointless or lead to super, super niche cases where someone survives thanks to it. Personally, I'd rather just see Carbuncle (and Egis) just "attack" when a Ruin, Rite or Outburst spell is used. Creating the illusion of it doing more would the game feel better at least.

Ruin IV isn't pointless, since it's instant and stronger than Ruin III and AOE. I think, this issue is rather related to Aetherflow being tacked on at this point. If Aetherflow was gained by summoning, being even stronger after entering a trance, I'd feel a lot smoother and integrated.

I'm just gonna ignore what you said about PVP because it doesn't relate to PVE balance. That is an entirely different beast of balance.
Crimson Cyclone is absolutely not too short. In fact, the range is longer than the dashes of the melee jobs. 25y compared to 20y that Spineshatter Dive and Hissatsu : Gyoten have, for example. It also matches the cast range of Ruin for consistency. Speaking of consistency, the ranged attacks of melee jobs have all the same range as their dashes.