What is this odd tool used for?

Following Lorel C's idea, I searched a bit for "patent" "kientz" and "foot massager", and found the patent for this device - https://patentimages.storage.googleapis.com/3b/09/3c/f580058fba56fc/USD243557.pdf

Short answer - yes, it's a foot massager.

If it is kitchenware, it's got to have an obscure decorative function, or else someone would have figured out the use by now, and it would not have obvious features designed for stationary use (the pads mentioned by NaniBly).

I say, not kitchen at all, but foot massager. It sits on the ground stationary, and you run your tired feet over it. (Assymmetry makes it more versatile for a variety of foot types.) Something like this:

For sale at Gearbest. No I am not affiliated with them.

Pastry fluting tool ... it could also be a meat tenderizer, I used to have something similar back in the late 50's that i used to roll back and forth over lower grade meat cuts to break the fibers down, not like the pounding ones that cut the meats. You could use it to flatten them for rolled meat recipes too.