Brass cone and wooden handle
Brass cone shaped top with a pivoting ‘knife’. The cone shows signs of rotational wear.
Pivoting blade
the knife is not sharp and probably never was.
Blade closed
The blade folds into the cone and reveals just a sliver of the back.
It looks like it might be some sort of a cork reamer for a barrel, but that would not explain the pivoting blade.
If you think you know what this tool is then drop me a line.
You are correct – here’s the followup post https://sawdustandwoodchips.com/junes-mystery-tool-revisited/