Historically, there are three broad grades of Japanese sharpening stones: the ara-to, or "rough stone", the naka-to or "middle/medium stone" and the shiage-to or "finishing stone". There is a fourth type of stone, the nagura, which is not used directly. Rather, it is used to form a cutting slurry on the shiage-to, which is often too hard to create the necessary slurry. Converting these names to absolute grit size is difficult as the classes are broad and natural stones have no inherent "grit number". As an indication, ara-to is probably (using a non-Japanese system of grading grit size) 500–1000 grit. The naka-to is probably 3000–5000 grit and the shiage-to is likely 7000–10000 grit. Current synthetic grit values range from extremely coarse, such as 120 grit, through extremely fine, such as 30,000 grit (less than half a micrometer abrasive particle size).
After you have completed a few passes over the stone on both sides, you can move to the final stage. This time it is P1 pressure, just enough pressure for you to control the knife. Ensure your stone is wet and now repeat the motions but with very very light pressure. You really need to focus here and ensure you are reaching the edge of the edge and again, just a few sweeps on both sides of the knife.
Edges lose their sharpness for the very purpose they cater to. Cutting acidic fruits and vegetables like lemon, tomato causes corrosion in the blades. Knives are often used to accomplish tasks they’re not meant to perform, like scraping or opening tin cans. Blade buckling is also a very common kind of damage your knife faces every now and then. It happens due to slicing items heavier than the knife itself or crushing ice. Keeping the knife in high temperature or washing it with harsh chemical based detergents also has havocking effects on the sharpness. Taking proper care of your cooking combat hunting knife is the only way to prevent it from fraying. Always select a suitable knife for the task, avoid heavy wooden cut boards and wash it immediately with cold water right after using.