I think I remember this getting answered in a lore thread somewhere, source unknown, so I'll write as opinion until fact-checked.
I've been under the impression that the amount of free-will a summon has is dependant on the arcanist. Almost like there is a gradient from [mechanical]<--------->[sparkly fluffy pet] and each arcanist's ability to summon a carbuncle/egi/faerie falls somewhere on that plane.
This is kinda shown in game with all the very stationary carbuncles in t Arcanist's Guild, that are basically just standing there, commandless.
I've been under the impression that the amount of free-will a summon has is dependant on the arcanist. Almost like there is a gradient from [mechanical]<--------->[sparkly fluffy pet] and each arcanist's ability to summon a carbuncle/egi/faerie falls somewhere on that plane.
This is kinda shown in game with all the very stationary carbuncles in t Arcanist's Guild, that are basically just standing there, commandless.