Sharpen knives and pruners—both hand pruners and loppers—with a whetstone. Don’t use a file or grinder, which will remove too much metal and wear the blade quickly. You can use a bench stone, diamond stone, or dry stone.
Small knives are most conveniently sharpened by placing the stone in a vise or on a firm surface and moving the knife over the stone. If a lopper is too awkward to sharpen this way, lock it in a vise and sharpen it by moving the stone over the blade.
Most pruners are easily disassembled for sharpening, and can be sharpened like a knife. If pruners do not disassemble, or for a quick touch-up of the edge, use a narrow flat or rat-tail diamond file that fits between the cutting edge and the anvil.
In general, sharpen all tools at the same angle set on them in the factory. Knives and pruners are usually set to a bevel of 25 or 30 degrees. After making a few laps across the stone, examine the edge to be sure the entire bevel is shiny from touching the stone. Unless the knife is very dull, a few licks on each side will restore the edge.
Holding the knife or pruner at the correct angle to the stone, push it across the stone edge-first. Make a few passes, moving the knife so the entire length of the blade comes in contact with the stone. Then turn the knife over and sharpen the other side. Sharpening creates a tiny bur of steel on the side opposite that being sharpened. Alternate sides as you sharpen, making a few licks on one side, then a few licks on the other side to remove the bur. As the knife becomes sharper, lighten your touch. The last few licks are very light, to remove any remaining bur.
Bypass pruners are sharpened on the beveled side only. After sharpening the pruners, lay the unbeveled side flat on the stone and remove the bur. Don’t put any bevel on the flat side, or the pruners will not cut cleanly.
Anvil pruners are sharpened on both edges, like a knife