This has been brought up before. I had a thread about anything physics of lightsabers.
http://www.saberforum.com/index.php?topic=30739.0In Shatterpoint, an EU book about Windu, the blade is stated as "weightless".
I see references to gyroscopic effect, weightless blades with fast building momentum and variations of those ideas eluding to the danger for an unskilled attempting to fight with it. Cutting or lightly sweeping as we see in film is different than battle. But, I don't see specific reference to stories these ideas come from.
Darth Maul: Shadow Hunter states the phrase "frictionless edge of a lightsaber."
In Book of Sith, Quinlan Vos states that lightsabers should have hand guards.
My real life experience tells me that gravity pulls the blade down in a way that helps me spin it. I like the center of gravity to be in the blade, not the hilt. Put two sabers together, and the staff seems to spin slower. It helps me to hold one hilt so the center of gravity is shifted to help pull that way. The actors will be dealing with the same forces. The characters may be dealing with gravity affecting an empty hilt, but the field emitted causes some kinetic disturbance on the blade. Once the blade starts moving, it may be hard to stop. Han can slowly cut open a Tauntaun, but spinning may be dangerous for him. Finn has weapons training. Rey has staff experience, and the director has a crush on her...I mean, she has the Force.