An actuator assembly for hand-grippable devices, such as levers for a brake or clutch, triggers, scissor-action tools, etc. The actuator assembly is a lever having a rotation-restriction mechanism, such as a one-way bearing, mounted on a shaft, with a sleeve assembled over the rotation-restriction mechanism and shaft. As the lever is grasped by the fingertips and pulled toward the operator's palm, the sleeve rotates about the shaft axis, thereby allowing the lever to roll from the fingertips toward the base of the fingers near palm of the operator's hand, where the operator has greater strength and control over the lever. The sleeve is prevented from rotating in the reverse direction, so, when the operator releases the lever, the lever slides along toward the fingertips, allowing the operator to slow the motion as desired. The actuator assembly reduces fatigue and loss of control over hand-operated mechanisms.