NerdFact: No the cross bar will not protect the wielder from a another light saber sliding down into their hand (unless they were to tilt it in time) because the opposing light saber will slice through that extended hilt, protruding at the interception, where it is unprotected.
(If used expertly then it’s added protection and a extension to the weapon. So knowing anyone using a light saber it will be put to good use. Can’t wait!)
If you haven’t seen this awesome trailer then check it out here! (I love vague movie trailers because a lot of trailers ruin movies for me)
Photo source Credit (Legion Of Potatoes, at Tumblr)