Ooops. To late. It's all I had in the garage other than Kiwi shoe polish. It and the sheath are way better looking than it looked after at least 10 years in the box. I do not think I have hurt it.
But after looking up Neatsfoot, it is as you say not the best for older leather.
Is there a way to safely remove it or just leave it?
Maybe go squeeze a Mink for some Mink oil??
From all the "internet" stuff I was able to research the Q was not for opening boxes, it was meant as a knife..