Stuck in the dark in the Star Wars universe, sans torch, you'd be able to make do. Blasters shoot glowing laser bolts and lightsabres... well, they're lightsabres. In fact, a Jedi wielding the Force would probably prefer to cut things up with the lights out, giving his or her gun-toting opponents quite the disadvantage. But what would it look like? Very pretty, actually.
The clip above, put together by ApprenticeA and directed by Corey Vidal, provides us with a rotoscoped impression of how a pitch-black combat between stormtroopers and a Jedi might go down. The sabres are the work of Genesis Custom Sabers, if you're in the market for a (fake) sword made from pure energy.
There's a behind-the-scenes video available if you'd like to learn a bit more about how it was put together. It's easy to forget that what amounts to just over a minute of footage took weeks to plan out and stage.