Maintenance of your whetstone
Your whetstone must be serviced from time to time too. You can buy various accessories for that purpose from knivesandtools.co.uk. A whetstone is maintained with a flattening stone or flattening block by Naniwa. The flattening stone evens out the whetstone when it has become hollowed out through use.
Accessories for whetstones
You also find guards for your whetstone at knivesandtools.co.uk. You mount those guards on the knife to ensure you always sharpen in the right sharpening angle.