I just became a master in Blade skill in Obivion, and my blade skill stopped increasing after that. It just stays where it is. I have used a lot but it's still there so is that normal or something wrong? Thanks a lot for help.

Master at skill level 100? If so, then that is the natural skill cap and it will no longer increase from usage.

You can sometimes find spells, scrolls or equipment that can boost these though . Some items stack together for increased effect too (like a Blade +5 item and a Blade +10 item would make a 115 total skill if you have both items equipped at natural skill level 100).