In designing, there are situation where a servo can be connected to take an axial load or a radial load.
I consider an axial load to occur in the case where a servo is used to rotate a load connected along the axis, like the pan direction in a pan and tilt configuration; a radial load would be like a knee joint.
Which types of loads do a servo handle best? Which is the preferred design?
The servos are probably designed for “radial” loading, as that is the type of loading the servo horns apply when normally used. “Axial” loading is not the primary design function of a typical servo, but they probably work well in this mode. Servos are probably not designed to normally take a heavy thrust loading on the output shaft (aka heavy weight sitting on the control horn). Servos are probably under the least stress when the only force being applied is rotational torque on the servo output gear.