Hi Steven C.,
Lot of good points brought up here, my 2c worth-- what condition was that blade in when the guy got it?
In this case, a before picture is worth a thousand words.
I have seen some ancient swords that for a lot of different reasons cleaned up real well. Mostly it has to do with whether they were dug and if they were what kind of earth they were in. Or if not, how badly did the air and moisture around them corrode them? Bottom line, you pretty well have to think about cleaning or polishing the oldies one case at a time.
Tim