I'm no expert, but a kit bought in 1980 would have rust on it if it was carbon steel. Unless, you've kept it in a very dry place wrapped in an oily rag. I suspect it's stainless, and if it is, what I'm about to say is useless. But, just in case....
Like Laurence says, vinegar works pretty good. But, I'd like to add to what he has said so far, at least as far as my experience goes. On carbon steels, heat the vinegar to near boiling, either stove or microwave, before submerging the blade. It'll start bubbling immediately if its carbon steel. If so, wait about 10-15 minutes, remove knife and rub it down under running water with your "clean" hands or an old toothbrush. A lot of the oxide with wash off, then put it back in the hot vinegar. Each cycle of vinegar/rub down will build up the patina more and more. After 5 or 6 cycles, it'll be nicely aged.