Is it necessary to use material harder than the knife edge? I could see a simple A 36 or 1018 steel rod being sufficient, depending on load. However its also possible that it would have to be moved after each test, if the edge were to make an indentation under high enough load.
One other thing to consider would be the ability to see where edge deformation is reduced or eliminated as a function of edge angle, when compared on the same edge.
One other thing to consider would be the ability to see where edge deformation is reduced or eliminated as a function of edge angle, when compared on the same edge.