Well if you think about it, maul was a sith apprentice at the time of his death and obi wan was a jedi apprentice, maul did i remember overpower obi in the duel, only arrogance and abit of shock killed maul. Really obi and maul were on parr, so if your thinking about grievous, i believe maul would own him. I believe that maul nearly defeated darth sidious in a duel once, in the comics.