Let me explain. I don't want (exactly) a term for veiled/secret messenger.
I want it to be a term that means a person has been granted the privilege of not being talked about, as if they were a veiled/secret messenger.
We would not want folks idly gossiping about where a secret messenger was going, or where they had been, or what they had delivered or been doing on their journey.
So, while a person might not actually be a "messenger", a king might want to bestow the privilege of same level of expected secrecy and discretion about a favoured person's comings and goings.
fanha- (v. to veil/cloak).
hûl (n. secret).
esgal (veiled)
mengyl (n. messenger)
said (adj. private)
dholen (secret)
Some options for secret messenger would be:
esgalmengyl (like esgalduin, veiled river)
mengyl dholen
I'm at a loss on how to come up with a phrase for the concept of "the privilege of secrecy."