I use files, if they are too hard for files I then use diamond files which can be bought cheaply enough. DMT make a range of rod files (diamond) these are the best I have come across. Sydeco make great ceramic sharpening rods, if you buy their V rod sharpening kit that is designed for sharpening kitchen knives then you will have 2 grits of rod 2 off each. I can recommend that for kitchen knives and you will have 4 rods 7mm diameter to sharpen other tools with.
you could wrap some silicon carbide (wet and dry) around a dowel.