Another one for Tim's 'Museum of Weapons Curiosa'!!
I really look forward to the stuff you come up with Tim! Fascinating.
I think Katana has a good idea on the bayonet blade, but this looks pretty worked down. I think in the direction of 'trench art' with many items fashioned out of spent ammunition casings, bayonets etc. The rifle barrel idea seems plausible too.
Possibly an officers baton? or swagger stick?