Here is a similar knife I have. Identical style blade. Almost identical touchmark. Similar style handle. This handle is dated 1748, and the sheath is dated 1762.
Well, shut the back door! Where was this one found?
There appears to be a set of hallmarks in the lower portion of the 'crest' (?) in the sterling silver handle. The 'lion' appears to have a a 'Dutch' feel about it, artistically.
The leather sheath is in remarkable condition, for it age, don't you think? What do you use to keep it in that condition?