Darth Maul is not the first non-human force user in Star Wars, Yoda is. A double bladed lightsaber is just two attached at the hilt. Darth Maul was more a pawn than Grievous, he only kills one Jedi, Grievous kills more than that, lays seige to Coruscant, abduct Palpatine, Kills the Jedi escorting him, ect..