T_C, It very well could be made from a file. When new and sharp files are used in the shaping and finishing of blades and then when old and dull they are often made into blades and other parts. Waste not want not.
Steve, I think you and Gene both might be on to something. He earlier said "The guard looks like its been made as a tool. One side elongated and pointed the other shorter broader and flattened. Could it be old enough to have been used alongside muzzle loaders?" And now your idea "Could the guard be used as a pick for the touchhole of a cannon or lantaka?" Very interesting ideas.
Robert