There's a lot of discussion going around about the new lightsaber in Star Wars VII. One criticism I've heard is that the cross-guard on the lightsaber doesn't look like it's going to do anything. One function of a cross guard is to stop your opponents blade from sliding down your own and lopping off all of your fingers. As you can see in the image below, there's a little nub of an emitter at the base of the cross-guard. Wouldn't an opponents lightsaber just lop the cross-guard right off as it slid down the blade?
With that in mind, what prevented people from losing fingers in the first place? Can lightsaber blades even slide against each other? This scene from the battle between Obi-Wan and Dooku seems to suggest that they can.