In case you didn't catch it in the international trailer (at the 0:49 mark) take a look at the image above. The cross guard lightsaber is legit! As you can see, the smaller blades will in FACT be able to cross and guard an opponents lighstaber, and keep them from getting their hands and arms chopped off.
Let me further explain with my own rendition of the saber.
As you can see, I have clearly pointed out that the lighstaber will have little "slits" in the tubing of the lighstaber, which exposes the laser of the smaller blades.