This looks a lot like the Storm Atronach from the Oblivion RPG. If you want to simulate the wild movement of that monster as it travels you will need to have a bone for each rock (the hands and fingers can be one thing).
My suggestion would be to have a normal FK or FK/IK armature for humanlike movement but have each rock mesh as an individual object, each parented to a bone that is in turn parented to the apropriate bone in the human armature( but not connected). That way, body movement can either be controled in a humanoid movement or the individual rocks can go flying about. Put the single bones in a layer by themselves so they can be selected easily and separately from the humanoid armature. You can have the rocks fly about and easily return them to their original human location by advancing an appropriate number of frames, select all the single bones, hit Alt-G (clear location) and key the result.