You don't need to ad more Egi's, just add Egi glamours.
What I would add in terms of new summons, is a counterpart to Bahamut:
Dreadwyrn Aether renamed to Trance Aether.
Enigma Trance
Decreases damage received by 10%.
Duration: 16s
Additional Effect: Resets Tri-disaster recast timer
Additional Effect: Removes the Bind effect of Tri-bind, increases its potency by 40, and reduces MP cost
Additional Effect: Removes cast time of Ruin III
Increases Trance Gauge when effect ends
Can only be executed when Aethertrail Attunement stack is 3 and Demi-Bahamut or Demi-Alexander are not summoned.
Aethertrail Attunement is achieved upon executing an Aetherflow action.
Cannot execute Aetherflow while under the effect of Enigma Trance.
Summon Alexander
Summons Demi-Alexander to fight by your side. Each time you use an action on a target, Demi-Alexander will execute Enigma Screen on a party member.
Duration: 20s
Trance Aether Cost: 2
Cannot summon Demi-Alexander unless a pet is already summoned. Current pet will leave the battlefield while Demi-Alexander is present, and return once gone. Cannot use while under the effect of Dreadwyrm Trance or Enigma Trance.
Enigma Screen
Erects a barrier around target negating 30% of damage received by the next three incoming attacks, applies to most attacks. (doesn’t apply to whole-arena boss attacks)
Will only execute while Demi-Alexander is summoned.
Enkindle: Orders pet to use their Signature attack. Orders Demi-Bahamut to execute Akh Morn. Orders Demi-Alexander to execute Final Judgement. (consolidated skill)
Final Judgement
Deals unaspected damage to a target and all enemies nearby it with a potency of 500 for the first enemy, 10% less for the second, 20% less for the third, 30% less for the fourth, 40% less for the fifth, and 50% less for all remaining enemies.
Additional Effect: Consumes any existing Enigma Screens for additional effects: 1 Screen = Stun, 2 Screens = Stun and Silence, 3 Screens = Stun, Silence, Slow and Bind
Can only be executed while Demi-Alexander is summoned.
Basically, Alexander would be a version of Bahamut tailored to trash mobs and defensive utility.