We bought a 1700's trade ax from a reputable Indian artifact dealer a couple of years ago. We know that the wooden handle is not original but the blade part is marked as coming from the Chequagua Falls area of New York State. We also know that the two small square markings on the blade mean it was made in France for trading with the Indians. However, there is another strike mark we haven't been able to find any information on: It's a shield shape with the letter "S" in it. Does anyone have any information on what that indicates?