Originally Posted by
Bhearil
The reason is probably the Primal“s aether ammount. Prime Zodiark had such ammount not even the Ancients could ward against it, meanwhile the rest of primals are tiny specks of aether in comparison thus easy to ward against, for beings of huge power like the Ancients aka having the Blessing of Light
When we face Zodiark not only is faction of his power, but also Fandaniel wants to crush us not tempering anyways, and when Luisoix was tempered was after he reliquished all the power he gathered, so his aether was overwritten with Bahamut's imprinting
Think on aether as water, if your own is a river, someone pouring a cube of different water wont change anything, but usually primals for normal people are akin to having a small stream being overwritten by a water inundation.
Seems Venat aether protection spell does not only affect the wearer but also an small area around them, thats why they can "shield" others from primals tempering