my 2 cents; the tang (nakago) seems to be shortened, ending square and I would expect it to be about the same length as the blade part. At the japanese sword forum Nihonto Message Board they have a translation help section, advice would be to post it there. Signatures often follow patterns, in this case possibly: Provence name -honorary title- smith name-"made by". Please let us know what it turns out to be
Oh, and maybe redundant; don't clean/sand/polish/whatever the nakago. Color and filemarks are indicators of age.
Kind regards,
Eric