Thanks Kutter for taking the time to comment. I believe yours is the first deeper explanation I've seen about why an engraver prefers a case hardened part to be annealed. Generally, it's just mentioned as an automatic passing step. I believe there are folks that will engrave, for example, a modern high alloy hardened stainless knife blade, but they probably wouldn't have to contend with the complications of a case.
Back to the topic, I asked about the high temperature anneal, because the usual recommendation is to pack a part in basically the same char coal. But, I'd think that annealing above critical temperature, in that manner, also drives more carbon into the surface of the piece. It may just turn out to indistinguishable, but on the other hand, occasionally parts crack. Thanks again for your comments, and to you again PhysDoc for the inspiration.
