Complex sentence: They do not exclusively bond themselves to either the light or dark sides of the Force, while a Dark Jedi can use Jedi and Sith Force arts with ease, they rarely obtain the mastery of either side.
Split into simpler sentences: They do not exclusively bond themselves to either the light or dark sides of the Force. While a Dark Jedi can use Jedi and Sith Force arts with ease, they rarely obtain the mastery of either side.