Be careful with ShadowKeeper - it's a powerful utility for editing savegames, but it will also let you screw up your game, as you just found out. It's a bad idea to edit class levels with it - use your game to level up instead. Whenever you want to try something new with ShadowKeeper, make an archive save so you have something to go back to in case things go wrong.
You can do one of two things:
- Go back to a prior save.
- Move your current game into the multiplayer savegame directory and re-start it in multi-player mode. Give your protaganist's items to another party member and remove your character. Create a new protaganist to replace him and save the game. Move the game back over to the Savegame directory. Use the Console (my preferred method) or ShadowKeeper to bump up his XP - but use the game to level him up.