It will sand out the worn area but, those frets will then be lower than other frets on your guitar causing even more buzz. It will not crown the frets afterwards, causing more buzz and most likely intonation problems. If you have a few frets that are worn, the rest of the frets need to be leveled to the same plane as the worn frets or, the worn frets need to be replaced and then they need to be leveled to the remainder of the frets on your guitar (depends on how bad they are as to which method I would use.) Over all, there is a good chance this tool will do more harm than good to your axe. There are a few more ins and outs of it but, those are the main points.
I would leave the frets to the pro's.