Soak in what? I don't have any rust cutter, so the next best thing? Vinegar. Just look around the garage for a suitably sized plastic container, plop a tool in and fill with vinegar. Nothing special, just simple, cheap, distilled white vinegar, I keep some in my shop for just such an occasion (and a few others, later on that).
After an overnight soak, simply remove the tool and wipe down with paper towel. You may want to use gloves simply because the black gunk that wipes off and whether or not you like having your hands smell like pickles. The cool things about the vinegar soak (apart from the science involved) is that it not only dissolves the rust but also both darkens the metal considerably and gives a protective patina to avoid rusting in the future (or so I'm told).
The metal is still pitted where the rust was, but the rust is most definitely gone. Notice how dark even the sharpened end of the chisel has become? Pretty cool, almost a gun blue effect. I wanted some further protection for both of my tools and took two approaches for each. For the chisel I took the age old standard of giving it an oil rub. For the blade wrench I went with some stellar Krylon paint.
The chisel looks almost the same after finishing but I know it will resist humid summer air with the oil thinly coating it. The blade wrench is a new blue and displays well tucked back into the shoe of my newly re-bladed light saber sharp circular saw.
Now for a bigger container to soak some of those bigger tools....