Before sharpening
The hand hones can be used to remove nicks before sharpening (if the skate blade is damaged). Two hand hones can be rubbed against each other to keep them flat and clean. Even better is to rub a hand hone against an old grinding wheel.
After sharpening
When a skate blade is sharpened to obtain sharp edges underneath, fine burrs will arise on the sides of the blade. Those burrs make the skate feel dull against the ice and increase friction. Use a hone (whetstone) to remove the burrs by pulling it evenly along the sides. Then you will have obtained perfect sharpness!