You do have to keep the blades of a lawn edger sharp in order for the tool to work properly. With some models, in order to sharpen the blades, you’ll need to remove them from the tool. Once they’re removed, you can clean them and then use a grindstone to sharpen them. With other models, the blades are easy to access while they’re still on the tool. If that’s the case, you can just clean them off and use a small grindstone to sharpen the blades.