What makes you think it's a Rev. War bayonet? By length alone it would be a very short bayonet. Most blades alone were 14-16". That said rev war bayonets were sometimes locally made so the design varied greatly. Good luck and I'm sure someone on here can help on an ID.
If it is bronze I doubt it is a bayonet. The end seems to be less than 1" in diameter. With that, It would not fit over the end of a Rev War period musket, which if a bayonet, it would surely have to. It even seems a little small in diameter on the round end for a period candle holder. It could be a lightning rod, conceivably.