A mythical pen (only he can see), 

so he can note down what he will do to his next wife.

The world largest cake -bigger than the Eiffel Tower-,

so that he doesn’t get hungry any time soon.

An emerald sword ,freshly sharpened,

so he can behead his next wife.

The brightest fireflies trapped in a jar

(with a wooden top made from the finest wood originating from deep in the black forest) 

to keep it light in a dark room.

A diamond ring (only seen if there’s no love)

so he can divorce another wife.