I have not removed etching exactly like that but have mirror polished some blades , by hand sanding, that had hollow grind somewhat like yours to get rid of grind lines .
One thing that helps in the hollow is get a THORN RESISTANT or HEAVY DUTY bicycle tube (a really skinny one like "700 x 23") and use a hunk of that to wrap the wet or dry sand paper around .
Stop by a bicycle shop and ask for one out of the trash ; they should be glad to help or give 'em a couple bucks .
And or you can stop by an auto body paint supply and get various density spot sanding pads . The bike tubes are curved and just the right density if you get the TR or HD ones .
Don''t be afraid to go really coarse to start with then use many grits to get the scratches out .
I mean you can experiment first with finer grits like 600 or 1000 but I'm thinking you will need to go much more coarse to make headway in a timely manner .
ALSO that is a polished blade so you are going to have to use many many grits IN PROGRESSION to get it to look like the opposite side of the blade .
Probabably at least up to 4000 , 6000 many higher . Do not skip a grit once you get the letters off . Otherwise scratches will show through the polish .