A guillotine.
Its a simple ansewr. ITS A KNIFE!
The instrument of death you are asking about was called the 'Guilletine' , and actually was nothing like today's paper cutting machine except for name.
guillotine.
Scissors
gillotines
The guillotine .
Guillotine.
The French Revolution.
They used the guillotine to behead them
The instrument you have here in question would be a variation of the guillotine. Once used as the instrument used in putting to death those sentenced to death. As a matter of fact, Spanish speaking persons use the same name for both, guillotina = the ancient machine of death and the modern hand operated paper cutting machine.
Scissors ? I suppose scissors was used during the French Revolution. But if you think about the device used to behead people : it is called the Guillotine.
The ax was used in the middle ages. The French guillotine wasn't invented until 1789 well after the middle ages and in the French Revolution.