The Sith Apprentice... Have you ever noticed the progression of Sith Apprentices parallel/mirror the progression of Anakin Skywalker to Darth Vader?
Episode I... Darth Maul... is pure hate.. an raw emotional double bladed killing machine.."Sith Weapon"..
Episode II Count Dooku/Darth Tyrannus is the "President and CEO of Sith INC".. Killing you is never personal..Just business..
Episode III Count Dooku/ General Grievous.. Lives a doubel life as Dooku and Tyrannus and CD is overconfident and too proud to believe he could be betrayed by his mentor Sidious and bested by Anakin Skywalker..
General Grievous is the master tactician, general. but his body is frail..protected by monsterous armor and duraskeleton..

If you put the three Sith Apprentices together... they are the Emotional and Physical aspects of Anakin Skywalker's journey in becoming Darth Vader.. and fortell Darth Vader's eventual defeat by Obi Wan Kenobi and his Rebirth into the black suit that is Darth Vader's blessing and curse.

Speak Softly and Carry a Big double bladed lightsaber!
THX,
CE