I was joking about Sephiroth having x-ray vision, btw.
I think Sephiroth probably has better eyesight than others, and can see very far away. He can probably see things more clearly/ sharper as well.
There is also a chance he may be able to see in the dark. Or at least see better than other people in the dark. He also probably sees more colours across a wider range of the spectrum, like Licorice said.