This is a spell editor designed to be used for WoW version 3.3.5a (12340).
You could update it to be used with other versions relatively easily, but there is no easy way for me to make it support many versions at once with the current implementation.
Downloads can be found in the releases section, please report any issues you find and I will look at them when I get a chance.
It currently supports SQLite and MySQL connection types.
The editing process is to import your spell.dbc into MySQL or SQLite, and then edit the spells from there. When you are ready to test the modifications you have made you can export it back into a new spell.dbc.
Enjoy.