I agree with Alberta Ed that it's a good idea to learn good hand sharpening. It is quite satisfying to do the job by hand. Also no noise and no need for electricity. A knife always works, so why depend on electric power to sharpen it? If you want a constant edge, there are various guided systems that allow you to get that by hand, although not quite 'freehand'. For just keeping your knife sharp enough to work, a simple ceramic rod will do.
As it's a pocket knife, I would say find a pocket sharpener - a small stone, a small slab of ceramic or diamond... I found that half a hardfoam nail file with two sides, one in 100 and one in 180 grit, will do to quickly touch up your knife and maintain a cutting edge when you are away from your 'serious' sharpening gear. If you also want to polish it, add a coin-sized little slab of ceramic or another piece of hardfoam nail file, this time one of those super-fine polishing ones. Your significant other probably has them. You can get them by the bagfull for a few bucks on Amazon, too. As they are not metal they will not damage your pockets, and they weigh next to nothing (backpackers will love this). That way you always have a basic sharpening option with you that offers a bit more than just the bottom of a ceramic cup or the top edge of a car window... ;-)