I could easily be wrong but that hilt, to my eyes, looks like every Roman/Greek statue I’ve ever seen. It’s pretty artistic and detailed and that was a Roman trademark beyond the man’s physical details.
If it is indeed ceremonial, the size wouldn’t really matter as it wouldn’t be battle oriented.
Well, if a Roman theatrical company were tragically blown across the Atlantic, that might account for such an object. In the days of shore-hugging, squared-rigged sails and oars for propulsion, I doubt there was a lot of room for it on board any vessel that was deliberately provisioned for long voyage on open seas. Maybe broken in pieces and used for ballast?