How obvious are the effects of Sanctioning? Is it possible to hide the fact that you're sanctioned to normal humans?
I always assumed that it changed your very soul in some way - so that another Psyker (or a Daemon) could detect that with the Psyniscience skill. Is that true, or is it just worthless headcanon?
I do know that many sanctioned Psykers go blind and such, but that's not 100% obligatory - others suffer less visible consequences (insanity, changed faith, loss of specific memories, coloration changes in hair/eyes/nails/ect, a few OCDs...). So this kind of thing does not really suffice to really prove that a psyker is sanctioned.
Second: Is it possible to be Sanctioned without going to Terra/seeing the Emperor in person? As in, can a large-scale Adeptus Astra Telepathica/Inquisition facility simply declare someone "sanctioned" if they have the power and knowledge to run all of the appropriate tests?