Psion
Adventurer
I mean guys with letters floating around there heads is cool to 5 year olds not adults
I'll start off by saying that the illumians will have to have more meat than "humans with floating runes around their head" to impress me.
But that said, I don't see anything "un-adult" or "juvenile" about it. I heard similar claims from people about IOUN stones, but never considered Vance juvenile fiction by any measure.