What they should have done with fairies:

[Iedarus]

-Remove Aetherpact and Fey Blessing because they're both kind of memes (Outside of Aetherpact in trash pulls)
-Eos's two abilities are Whispering Dawn and Fey Illumination (Illumination defends against all damage types and boosts all healing abilities)
-Selene gets two new abilities called Whispering Dusk and Fey Consecration
-Whispering Dusk is a targeted AoE (Just like Gravity) which inflicts all enemies in the area with Whispering Dusk that does damage over time. If the initial target is already afflicted with Bio/Bio II/Biolysis, spread that DoT to the surrounding targets, as well. Basically Bane and Miasma in one.
-Fey Consecration is Shadow Flare (Minus the slow)
-Essentially Selene possesses the three missing Scholar abilities which made it fun, but in a much more streamlined fashion
-None of the fairy abilities deplete Fae Gauge
-Embrace is targetable by having the ability in the ability hotbar and pressing (toggling) it while targeting the desired person

-Fey Gauge has a new mechanic where filling it up to 100 unlocks the ability Summon Seraph
-Summon Seraph functions as an ability where she is summoned briefly and casts a spell that functions as a beefed up Consolation and an AoE DoT called Condemnation (To prevent ability lockout). This would essentially be Assize/Afflatus Misery but with a DoT and more impact.
-Seraphic Veil is called Consolation for name synergy

I'd also love if they remodeled Seraph to make her look bigger and grander (Bahamut size) to really look like an ultimate summon, but that's just me.

Edit: Changed Whispering Dusk idea, Swapped Illumination and Blessing, and cleaned up the Seraph portion