If you have a carbide tipped saw blade, you have an excellent tool for sharpening a knife quickly and easily. Just clamp it to a tabletop or lock it on your saw's arbor so it cannot turn.
Step 1: Draw the knife edge against a carbide tooth
Draw the cutting edge of the knife against a front corner on a carbide tooth. You do not need to use a lot of pressure. A few repeated passes will do wonders to a blade. The green lines represent the angle of the tooth face and the angle at which the blade is held. The brown lines represent a vertical line and the angle from the vertical at which the knife is drawn across the corner of the carbide tooth. Draw the knife slowly. Hold the blade with two hands to keep the edge on the relatively small corner of the tooth.
Step 2: Do the other side
After a few strokes on one side, turn the knife over. Use the same angles relative to the carbide tooth that you used for the first side, but draw the knife from the other side of the saw blade. Alternate sharpening one side of the knife blade and then the other every few strokes.
Step 3: Test for sharpness
I have often seen people pull a knife edge across the soft skin on a fingertip. That is a sure way to receive a cut. Much better is to scrape the blade laterally on a fingernail as shown by the green arrow. If the knife is sharp, a curl of fingernail will roll up in front of the cutting edge. If the knife is not quite sharp, powdered fingernail will gather in front of the cutting edge. If the knife is quite dull, nothing will appear in front of the cutting edge. Test at various points along the length of the cutting edge. Some parts of the cutting edge will be more dull than others and will need more attention.