Electrolysis is a great rust removal technique, but it's kind of a PITA to setup if you're not super handy.
An easier method, that is nearly as gentle, is plain "white vinegar". I use it daily to remove forge scale from the knives I make, which saves me money on grinder belts, and files.
Simply immerse the tool or whatever you're cleaning completely into white vinegar, and let sit for a few hours, or days, depending on the level of rust. Clean after removal with water and rag, dry completely, then oil. If left long enough, it'll leave a dull gray color to the top layer of the metal, which is a mild patina that will actually protect the metal. However, if the knife is a highly stain resistant steel (which will of course still rust in time), it will resist the acid completely, and maintain it's bright color.
However, for removing minor rust from a knife, I recommend using a Scotch Brite pad. It's easier and more effective than steel wool IMHO. In fact I use large belts for my grinder made out of the same material to put a satin finish on a blade.
Rub it in small circles over the entirety of the blade to give it a nice gentle sheen. The over the counter scotch brite type pads are non abrasive, and will only leave very light pattern scratches. Using a stone to remove rust can be very tricky on complex geometries, and can remove a lot of metal.