I checked Wookiepedia (because no matter how much of a loser I may be, there are always bigger nerds out there) to see if the crossguard lightsaber had any precedent. The closest, seen here: http://starwars.wikia.com/wiki/Crossguard_lightsaber, looks more like a sai than the broadsword look of the trailer, designed to tangle an enemy's lightsaber and possibly disarm them. The most obvious problem is apparent in both: the enemy's blade would be naturally directed into the corner between the emitters, which you may notice is not itself a lightsaber blade. Thus, the enemy blade would cut straight through the opposing saber, and likely a chunk of the enemy's hand too.
Come to think of it, given how often Jedi get their hands cut off, maybe this is some sort of mocking reference to that. Probably giving them too much credit.
Come to think of it, given how often Jedi get their hands cut off, maybe this is some sort of mocking reference to that. Probably giving them too much credit.