Originally posted by General Kaliero
Lightsaber-like energy. It's specifically the energy field that stops it, like the force fields in the other movies. Was speaking more on physical objects. The writers originally wanted them to be cortosis staffs if I remember correctly, but Lucas made them change that, too.
Its got some other type of alloy as well, there is a physical material. Lucas wanted something that could combat a lightsaber, something that just wasn't a sword.