Looks like an old Lancet style blade on a bullet jacket ferrule.
I'll give you $5 for it (and you'd be a fool to take it).
If it's a Stemmler it's a real find. It's reminiscent of a 1929 Stemmler (ABCC #1204.000) but someone like Raghorn who is smarter than I will hopefully come along with a proper ID.