Looks like rust. Scales look like plastic so probably not Cell Rot unless stored with an off-gassing razor.

You can tape the etch with a layer of Kapton, clear packing or Scotch tape, then cut around the etch to protect it. Then polish with a good metal polish and 0000 steel wool. When you get close to the tape, pull off a small piece and tape it to an eraser shaped to a point, like a chisel. Cut one with a razor blade and polish close to the tape and etch.

You can also remove the tape and with the pointed eraser and a dab of polish lightly clean between the lines of the etch.