HEUREKA! Finally at least a small path to follow to the light of knowledge
@katana:
The blade of your foil was most probably forged by a company named Cooper-Goodman. They produced the Chassepot bayonet (which was used between 1866-1874 by France but found many other countries copying it)...
Check out this link (you can see the similar marking clearly):
http://www.old-smithy.info/bayonets/1866_chassepot.htm
This information might give a rough idea when the foil might be produced. If one takes into account that the firm might not be active for a long time, and might not have much experience with fencing weapons (referring to the strange POB), this could indicate that the foil may be quite rare....
So far for now.
I hope someone can carry on the torch and finds more information on the firm itself.
William