This was apparently Jesus way of teaching us that our rewards are commensurate with our faith:
All Scriptures are from the King James translation.
In verse 24 the man could see but only partially, that was probably because he had heard of Jesus healing power, but was still skeptical.
In verse 25 he had experienced Jesus healing power, and then expected that Jesus did have the power to completely heal his blindness, and the second time he had full faith, and was completely healed.
We have more information about the rewards being equal to our belief in:
Matthew 9:28 through 30
28 And when he was come into the house, the blind men came to him: and Jesus saith unto them, Believe ye that I am able to do this? They said unto him, Yea, Lord.
29 Then touched he their eyes, saying, According to your faith be it unto you.
30 And their eyes were opened; and Jesus straitly charged them, saying, See that no man know it.
We today are privileged to see that truth demonstrated in the lives of the faithful, Have you noticed that those who are the most dedicated to the Lord have the happiest marriages and are the richest in his blessings?
Even though the most of them are not well off in worldly goods they do have all of their needs met, and they seem to have an extra measure of peace and happiness.
Those people also seem to be content with what the Lord gives them and are never envious of others worldly possessions, but are genuinely happy for the others gains, just as Jesus decreed in:
Matthew 6:8 Be not ye therefore like unto them: for your Father knoweth what things ye have need of, before ye ask him.
So taken together we learn that:
God already knows what we need, and he will give us our needs, but there is actually more to it than that.
Jesus also told us that we should ask the father 'daily':
Matthew 6:11 Give us this day our daily bread.
Jesus said in Matthew 9:29 (above)"according to your faith".
Several years ago four friends and I decided to put those scriptures to the test, and began by agreeing that to start with 10% of everything was God's portion, and that if we were to make an offering it had to be more than that 10%. None of us was well off by earthly standards, and as a matter of fact we were actually only living from paycheck to paycheck. None of us thought we could get by even giving the 10% let alone anything over that. We did agree though that we would start by giving that 10% right off the top.
I am sad to say that I was the only one who began by keeping that promise at first. At the end of the first month we got together again as we had promised to do, and compared how we were doing. After the first month I was the only one who had met all of my bills and still had money left over. As a thank you to the lord I took that overage and had the pastor give it to someone needy.
The next month all four of the others followed our agreement and each found that they finished the month with a few dollars left over.
Since that day we have all continued in our agreement of giving our tithe first and when we have extra give some to the needy, either through the Church or some charity, and the five of us have not had financial worries since, we are far from being wealthy, but we are happy and content and peaceful.
My reason for telling you this is not to start a stampede to give, but to let you know that Jesus meant exactly what he said, and if you take him at his word and trust him he will show you blessings commensurate with your faith.
I do feel it is necessary to tell you that we did not do this just to test whether or not the Lord would give us the desires of our hearts, but to see if our condition would improve despite no other things changing, such as some unexpected income, or bills being mysteriously lowered. I cannot vouch for the others but in my case it was to demonstrate that I had enough faith to trust that God would meet my needs, which he did. I hope that the others faith was strengthened enough by my circumstance that they also expected that God would meet their needs.
Not only that but just as with the blind man in verse 24 he will strengthen your faith as you see him give blessings in accordance with the trust you place in him.