There was a design in shopnotes that had a waterstone holder jig. This jig allows you to hold the stone and clamp the jig to the workbench. Wedge is tapped in place and it securely holds the stone while sharpening your tools on it. A buddy made one and I liked it so I built my version. Here it is. It is made from wood I had around the shop and finished in clear Spar Urethane.