Here are pictures of my engraved M-29-2. From reading the Nahas/Supica book, I assume the RS marking on the right grip frame is for Refinished Standard, but I cannot find a good reference to the "E in a circle" on that same side. Any help will be appreciated.
Refinish stamps are found on the left side of the grip frame inside of a rectangle. There will be a date code also that is shown in the picture 5 73 for May 1973 . This refinish was for bright blue that is shown as R-Bi.The letters on the right side of your gun are fitters and inspector stamps.
I don't think your 29-2 was done by S&W. They would put a smaller logo on the left side. The only way to know for sure is to letter the gun.