A dummy prop is a pseudo prop for looking, linking, attaching or reaching targets. You may use them to offset the aim away from the main objects. In addition to that, an object with several dummies attached can have the character hold it firmly with both hands. By using the dummy prop, you can mix up the path keys with separately recorded move, rotate and scale keys by puppeteering.
Please note that all the dummy props can be shown or hidden in the 3D preview window for editing, but they will not appear in the exported media.