Motley are associated with Poverty Point and not found anywhere near NW Missouri.
Kay Blades (not Kays), are pretty much a larger knife version of the Cupp point. They are named after Kay County, Oklahoma, are Mississippian in age and are often found in caches. It's a fine line, differentiating the Cupp and Kay blades, but Kay are larger (3"-4" on average) and the stems are generally more slender. They have a similar distribution range as the Cupp, but are most prevalent in the western fringes of the Ozarks, along the Grand / Neosho waterway, it's tributaries, and northward up to NW MO and NE KS.
I agree with Neanderthal, I think it's a Kay. Motley generally has stronger ears and the base flares a bit more than Motley. Also, as Neanderthal says, they're a marker of Poverty Point. You can find an occasional point in Southern Missouri. I don't think it would be impossible to find one in northern Missouri but it's be an oddity. Nice find.