No saving that poor Buff. Looks like a dug coin or detector find.
Nothing you do will improve the appearance, unfortunately, except perhaps a very long soak in virgin olive oil, which can take weeks or months and will need to be changed out every once in awhile.
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ANA - EAC - TNA - SSDC - CCT #890
"Most of the things worth doing in the world had been declared impossible before they were done." -- Louis D. Brandeis