Catheter shaft handles and deflection actuators are disclosed. The actuators include at least one pull wire guide wall and a means for anchoring the proximal portion of a pull wire or of a fiber attached to a pull wire. Each actuator is pivotable relative to the catheter handle housing, and may comprise at least one boss for pivoting the actuator relative to the catheter handle housing. The actuators transfer rotational motion based upon user input on a boss into longitudinal motion of a pull wire. The actuators may include a tensioning mechanism comprising a tension adjustment pin and a pin block, wherein the tension adjustment pin is rotatably attached to the pin block to enable adjustment of tension in a pull wire (e.g., during assembly of the catheter handle).