I haven't ever heard this proverb. There is a proverb, "There are none so blind as those who will not see." Is that what you meant? In any case, your statement is playing on two slightly different meanings of the word "see." Literally, "to see" means "to use your eyes," "to detect things around you by using your sense of vision." Figuratively, "to see" means "to see with the 'mind's eye,'" to understand. "I don't know why this equation has more than one solution." "Well, what happens if you square a negative number?" "Oh, I see now." Your sentence means something like this: "a person who is literally blind--but has an open mind and can accept new ideas and understand things--is better than a person with healthy eyes and normal vision--who refuses to consider new ideas."

This is a play on the metaphorical meanings of "see" and "blind". Often, people will say "I see" to indicate that they understand what was just explained to them. Even if it's not something that they are actually looking at, they "see" the connection between two things. For example, after explaining this, I could ask you: "Do you see how that works?" You didn't see anything, but you might understand it now. In the opposite way, someone can be "blind" to a certain event. It has nothing to do with actually seeing something, and everything to do with acknowledging or accepting that something happened. "The teachers at my school are blind to the bullying problem." That is, the teachers don't acknowledge that children are being bullied at the school. Now let's look at the proverb. "A blind person who sees is better than a seeing person who is blind." A person who is literally blind who sees [who understands things] is better than a person who is not blind, but acts blind [refuses to acknowledge things around them].

Blind people often develop their other senses very acutely, and have surprising powers of perception. The challenge of their situation can lead them to seemingly superhuman feats. Seeing, 'normal' people often take the world for granted, and have little awareness of what is around them.