Your maintenance tip gives me questions. You say the coticule strokes remove very little material, yet it is enough to remove 30x visible chips.

The issue sounds a bit confused, micro-chipping and micro-rust. While inter-related in many ways; they are separate issues. To help with rust try adding some baking-soda to your rinse water. If this helps you know it is acidity that causes the excessive oxidation.

More than one razor does this?

Is it vintage? heavily restored? Swedish?

I have found, even though I don't see any trouble, that after 3 or so good honings a vintage razor that suffers mchips settles down.

if it was heavily sanded, could be the steel is thinned down too much.

I have one swedish razor that seems to be more prone to tarnish than all others.

I agree with Sham that a layer or two of tape may strengthen the edge enough to stop chipping.