I would call that a "cotton knife," based on the blade shape, although that is now more frequently called a "cotton sampler" blade. It is similar in some respects to the blade shape called a "rope knife." I am not familiar with Grayson as a cutlery company, but I would agree that is what appears to show on the blade. I checked the references I have on hand, and could not find Grayson in any of them, but I have one more online resource to try.
The McKinley Tariff act of 1890 required that the name of the country of origin be placed on imported goods, so I would guess it is either pre-1890 or possibly of domestic (US) manufacture. The 8th and 9th photos in your first post appear to show some "pith" in the inside edge of the handle scales, which suggest to me that they may be antler (stag) with the rough outer surface polished off, rather than bone, but I could be wrong. The criss-cross design on the handle has the appearance of being hand-cut, which (I would think) would be consistent with a pretty remote date of manufacture. In his book,
Pocket Knives, Bernie Levine shows an old Sheffield folder by Samuel Wragg that is similar to your knife in some respects, and he suggests a date range of 1830's to 1860's. That is certainly not definitive, but I would like to think your knife might fall into the same range.
I'm not much help, really, but the "feel" I get from that knife is mid 19th century. It certainly has the appearance of great age, yet it appears to still be usable. It is a great old knife, in any event. Thanks for showing it!
Notchy Bob
ADDENDUM: I did find this, in
Trademarks on Base-Metal Tableware, by Eileen Woodhead:
However, I don't think it is the same Grayson. Dang it...
Notchy Bob