Blind or not the Onta is still there. For the Few, their awareness of metaphysical topology is strong enough to impinge on their mundane perceptions, so they are aware of it despite the immeadiacy of regular sight. If I recall correctly, Xinnemus glimpses something of the Cish when he is escaping with Akka, yes?
Sight dominates our perceptions and it is very easy to be deceived by visual illusion, even when we know better.
Inclined to agree with Wilshire here. Further, the third sight may be accessible to all to some extent. This could explain how the Cish are initially drawn from a single tribe.
Madness, I address how I believe Meppa sees the ontological reality of Psatma in the 'Sorcery' thread. The beggar need not be of the few, just slightly more sensitive to metaphysical reality because his perceptions are not cluttered by sight. I can easily see the white-luck appearing as something very intense to a Cish or Mimara. Noisy, if you will. Even that beggar, with no other abilities beyond the mundane is shocked to suddenly 'see' this walking intersection of metaphysical influence.
We don't know if Ganus was human, nonman or inchi. I have a sneaky suspicion he was a pre-apocalyptic Inchi. But the ability to 'see' prophecy seems very likely to tie into some sensitivity like that of TJE.
Imagine if Mimara was blinded and learned to 'see' solely via the Onta and the JE... crazy!