I've studied a bit of kenjutsu (Japanese sword), of which it is not uncommon to see blades without hand guards. While it might look cool to have two sword fighters straining against each others' blades staring menacingly at each other, and where as John described it's easy to get your hands and/or fingers loped off, one does not try to actually block the opponent's blade by preference. The goal instead is to deflect it past you, as this presents an opening to attack.

I'd also like to point out two things regarding the hand guard idea: First, if the hand guard was made of shaped plasma as the blade is, it would probably be a higher risk to the user than not having a hand guard at all. Bad enough to have to concentrate on never touching your own blade, but accidentally bending your wrist the wrong way and loosing your hand...? The second, given that the first point kind of kills the idea of a light hand guard, is to use Coriolis fiber, which is mostly resistant to lightsaber damage. Not perfect but if you screw up and let someone actually slide their blade down at your hand it would probably save you the first time...

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Oh, good. Spam comments that steal comments from the actual article. Okay, okay, let's address this as if it were a real, honest-to-Cthulhu comment...

- I'm sure it doesn't have to be an enclosed handguard, like a foil, especially since they're not fighting in fencing style. It could just as easily be a little v-shaped nub above the handle to catch the blade, or even a little light sphere to prevent the blade from sliding all the way down

- If they were fighting in Japanese kenjutsu style, that would be awesome, and would totally explain away the need for a hand guard, but they clearly are never fighting this way

- It's 'cortosis' fibres, not 'Coriolis', but I get you. It'd be a good idea, except only for us rubes with no Force powers, who can't yield a lightsaber properly

- Man, I'm being geeky