I have a steel straight edge. It is stored near (and not that near) 3 small rare earth magnets (in a sanding jig). Today I was looking again at concavity in straight razor spines. I noticed this: several of my razors do not respond the the weak magnetism of the straight edge, and some will pull to the straight edge when that edge is close to the spine.
I'm putting the question here as it must have something to do with the composition of the steel.