Free Hands
A free hands weapon is unbalanced or otherwise awkward to use. This difficulty in using the weapon can be negated by moving the listed number of hands that are not holding anything or being used for any other purpose as counterweights. You wield a free hands weapon using the normal number of hands, but if you have the listed number of free hands available while wielding it, the weapon is not considered unwieldy. For example, a kasatha wielding a flame spinner in two of her hands while her other two hands remain empty treats the weapon as though it does not have the unwieldy weapon special property.
Source
Armory pg. 28