I'll preface this to say that I know enough of the rumors to quash pretty much any hopes that Ahsoka was the hand-offer of the lightsaber in the new trailer, but at the same time I don't recall reading about Leia ever being presented a saber in any of the rumors and the teaser really strongly suggests it was her. It would also be a total waste for Lupita Nyong'o, a dead ringer for Ahsoka if ever there was one, to mocap a little blue bartender.
Thematically, wouldn't it makes sense for Leia, having just discovered that Vader is her father and full of questions, to go to the person who knew him (and also her mother) best when he was at his best? And by extension, in that scene she would be literally receiving her father's legacy (Anakin's lightsaber)? And wouldn't that person have orange skin and be aged and shrivelled a bit like the arm in the trailer (not to mention that particular fashion sense)? And wouldn't she be the perfect person to have helped Luke try to restablish some sort of order and later display some significant force powers as suggested by the rumors? My inner fanboy is getting the best of me despite my better judgement.
