Nice old cutter. Does it hold a good edge? Just curious. I remember a lot of cheap knock-offs in that era. But they didn't look nearly as good as yours.

A steel wire brush will take off the rust, but scratch things up as well.

I recently cleaned up a number of chisels and saw blades with a little paint thinner and a brass pot scrubber brush (most houseware departments carry them). The brush got right down into the rust pits and cleaned them up nicely without scratching. The paint thinner seemed to help loosen the rust without damaging the handles. So, a pretty fast but low-risk cleanup. I was quite happy with the result.

My $0.02

EDIT: just to clarify, the brass potscrubber brush I'm talking about is arranged like a fine wire brush, not like a blob of steel wool on a handle. Seems there are both types out there.