Immerse the whetstone in water and let it soak for five minutes.
Remove the hose-cutting blade by taking off the screws with a screwdriver.Wear your safety goggles and work gloves.
Stand the blade on its head with the cutting edge facing away from you. Move the wet whetstone back and forth at an angle of 45 degrees against the cutting edge of the hose-cutting blade.
Step around the blade and sharpen the other side of the cutting edge with the whetstone. Take care to keep the whetstone wet and the cutting edge of the blade away from you.
Hone the cutting edge sharper with an upright grinder. Use the grinder to remove any burrs on the blade.