Saw and tool sharpening is a craft form that can be learned for personal or professional use. At one point in time, a knife or blade sharpener would cart through a neighborhood to sharpen any saw or blade tools that may be in need of refreshing. Blade sharpeners can sometimes still be found where a market has sustained demand for blade sharpening. Saw and blade tool sharpening can be learned through an apprenticeship, taking a course or self-study.
Purchase books on saw and blade tool sharpening. "Sharpening: The Complete Guide" by Jim Kingshott, "The Complete Guide to Sharpening" by Leonard Lee and "The Art of Saw-Filing, Scientifically Treated and Explained on Philosophical Principles" by H.W. Holly are a few selections that will provide good stating points for modern sharpening techniques accompanied by pre-modern lessons. Lessons will include the physical theories behind sharpening, differences between grinding and sharpening and sharpening methods for different tools. Read as much as you can on the subject from as many different sources as possible. Take notes and practice what you have learned on tools in your own workshop.
Take a course on saw and tool blade sharpening. Foley-Belsaw has offered courses in sharpening for for more than 30 years. The course used to be held in a workshop and is now offered online. The online course is self-guided study and is based on the use of the Foley-Belsaw 1055 Sharp-All tool.
Contact a saw and blade tool sharpener near you. Ask if you can apprentice in the craft of saw and blade tool sharpening. Offer to apprentice for free or work as a hired hand. Look to apprentice with sharpeners who can train you in manual and machine sharpening to gain versatility from experience.