As a knapper of arrowheads I will admit to not quite understanding the proper use of a knapping hammer. Attempting to strike flakes off the gun flint as one would normally do from a spall or preform in traditional knapping seemed awkward and ineffective. That was until reading the product description at TOW. I never would have thought of using the little hammer this way.
"Place the hammer at half-****, and gently strike the front edge of the flint, square-on. This straight-on blow chips the upper and lower edges of the front edge, revealing a sharper edge. "
https://www.trackofthewolf.com/Categories/PartDetail.aspx/111/1/HAMMER-FLINT