I believe that balancing pet classes is a nightmare.
But I also believe that just because one job functioned a certain way in previous games doesn't mean it will function the same now.

However if you are going to implement summoner in the coolest and most iconic way. Summoner should be a spike damage pet class just as it was in most FF. This should take precedence over lore or current systems. Change the lore, separate summoner from arcanist if that has to happen. My friend thought it was stupid and sad she couldn't level summoner from level 1 anyways.