Well, to be quite honest with you, they are worth very little. The protypes might bring asl little, but parker knives, and the brand variations (partnerships, etc.) are far and wide. The market use to be "flooded" with his knives, whether they were his eagle brand, parker-brothers, parker-edwards, parker-frost, etc. They use to say that "small" numbers were made, but the nubmers that were in the market, tended to sate otherwise.
I remember when they first came out, they were popular for a little while as they were inexpensive. Much like the "rough rider" knives at smoky today (except the parker knives were a "slight" notch above the rough riders).
It was parker, and his associated books that rated his knives much more than anyone else ever has (or would). It would not hurt to polish it, but if you do, take into account almost all those knives had a satin finish, not "mirror" polished. You could take some fine emery cloth, maybe 800 grit, and use a little oil for a lubricant and rub back and forth from knife edge to the back of the blade, to match the original finish.
There is not much of a collectors market for his knives out there. They can (and I have seen them) go anywhere from 6-35 dollars, sometimes more, but very rarely (maybe for one of his hand made tak fakauta knives, but I wouldnt expect a premium).
Only in His books, and ones associated with him, will you find the ridiculous "inflated" prices.
If this knife is not in very good mint condition to begin with, surely it will not hurt it much at all to clean it up.
Afterall, you would be hard pressed to find a "devoted" parker collector out there who would pay a premium for it (especially in less than "mint" condition). This is coming from over 25 years of knife collecting experience.
