Mysterious object

[kronckew]

Your definition of broad and serrated vary from mine. They also wear down narrower as you sharpen them. You should have seen my Granny's:

How long it took from 'before' to 'after' I always wondered as all our butter knives were sharper. I suspect she had them at least 50 years...

The site I found it on just called it an old reaping knife sickle. Further definitions said they in general could either be serrated or not. My example was not. I suspect it was British victorian.