Just a quick post - not from myself, but from my Sensei (she is having some difficulties posting at the moment):
Hi, Jakob B! I have a blind aikidoka in my club. He did judo 20 years ago
when he could see, which has helped him with ukemi, but when he first came
to my class, I would get him to put his hands on my shoulders when I did
the technique, then again on my hips, and finally - slowly! - on my feet,
so that he could feel where the action was taking place and what direction
it was going. I also did the technique on him, so he could feel what was
supposed to happen. As for strikes, his partners put their hand on his body
(side of head/chest) as appropriate, and as soon as they draw back the hand
to strike, he begins the technique. It seems to work, he just passed his
first grade and is working towards the second!
Please give your potential student as much help as he needs to begin with,
as it must be awful to be blind, and aikido is such a fulfilling way of
acquiring some positive power in your life.
Good luck !