The saber is the equivalent of Chekov's gun.
Anton Chekov wrote that an author had to "Remove everything that has no relevance to the story. If you say in the first chapter that there is a rifle hanging on the wall, in the second or third chapter it absolutely must go off. If it's not going to be fired, it shouldn't be hanging there."
What this means in terms of the broad sword is that its a deliberate action for it to be in the film and in the teaser trailer. It's not there for some cosmetic effect or as an exhaust as some have suggested, it's there as a broad sword - and that means its functionality will play a part in The Force Awakens.
Forget that it could be chopped off and rendered useless as many have suggested. Kasdan and Abrams are not that stupid, nor is Lucas who has been keeping an eye on things behind the scenes as a creative consultant.
This writer wonders about a more different question regarding the sabers in the new film - will they add to or debunk the theory that the Star Wars movies are inversely as good as the number of times a lightsaber is ignited.