I had never heard of using Boric Acid for an etch before. Thanks Toby for sharing your technique. I recently bought a 5lb. tub of Copper Sulphate which I guess will now be used to kill tree roots in drains or prevent black algae growth on roof shingles. The CuSO4 did seem to bring up the Damascus pattern better than not using it, but I'm concerned about the weak adherence of the flash plating 2-piper mentioned and the potential for loosening jointing or precipitating into pits that Toby mentions. But if flash plating of copper occurred on both the iron and steel, rusting could not happen since copper doesn't rust. I had some old lathe tool-holders that ended up with a thin copper wash after I suspended them in an HCl pickle by copper wire. It seemed to prevent them from rusting.
