My personal opinion is that they should axe the Egis entirely and replace the Summon actions with "Summon Demi I/II/III" and you can assign whatever Primal you want to the Summon Demis in a Summoner-specific menu. They all have the same effect, but they're your own flavor.

Summon Demi I can be a high damaging single-target attack. Summon Demi II can be a defensive buff. Summon Demi III can be a small/moderately-damaging multi-target attack.

So, for example, using Summon Demi I will cause the Demi to appear on target's ring and do a very obvious single target hit. Think Ifrit's Incinerate, Titan's Mountainbuster and Garuda's Slipstream (I'm aware these attacks cleave normally, but they're SUPPOSED to only be taken by a single target). Summon Demi II will have the Demi appear above/behind/around the Summoner, doing something to protect the Summoner, like Ifrit curling his arm around them, Garuda shielding them with her wings or Titan summoning a wall to guard them. Summon Demi III, meanwhile, can be their obvious targeted-AoEs... Ifrit's Eruption, Titan's Weight of the Land and Garuda's Aerial Blast.

And, obviously, the other Primals that you defeat and assign can have their own versions of the attacks, but they all have the same effects/potency, so it will prevent skill bloat.