Armature springs configured to be coupled to and bias an armature of a torque motor valve actuator to a null position are provided. The armature spring comprises a rigid central portion, opposed end portions, and a flexible portion intermediate the rigid central portion and each end portion. The rigid central portion, the opposed end portions, and the flexible portions define a variable cross section torsion bar with the flexible portions comprising reduced cross-sectional portions of the torsion bar relative to the rigid central portion and opposed end portions. Armature assemblies and torque motor valve actuators are also provided.