If I am not mistaken red iron oxides have been used on razors for many years.
Check out some of the abrasive pastes offered at www.classicshaving.com .
They have also used the black pastes, graphite. The graphite works, I have used it, and also rottenstone (decomposing limestone). They both work and both are generally regarded otherwise. I will also be trying titanium oxide and tin oxide. I will let you know the results.