Large Old Unmarked 'Butter Knife', Very Sharp

The blade is carbon steel, the grip silverplate on brass. The fancywork at their joint is designed to keep the blade off the table, as the grip is heavier. The edge isn't so much sharpened as wedge-thinned to a cutting fineness, an' that sharpness extends throughout the end radius to the spine, then gets thicker to the heel; from ~0.020" to ~0.075". Overall length is 10", blade is 5 1/2" by 15/16".
Can any of y'all say if this pattern/style is European or American, an'/or when it was popular? I've put quotes around butter knife because smaller, an' much duller blades of similar pattern are familiar to me for table use in slathering butter on bread, etc...but the cutting edge is a puzzle. Thanks for lookin'!