Cutlery is a hobby, and I donate knife sharpening coupons for school and church fund raisers. I used a file for years on mower blades but now use a 2 in Sears belt sander for most things. I'll even use it on larger knives for the rough grind, but always finish off with stones, sticks, strops, etc.
In cutlery 'grinding' almost always done with a belt sander, as the typical rough, hard grinding wheels on bench grinders will get the material too hot, blue it, and lose the temper. It's also a possible problem with a belt sander, so you monitor your work and cool as needed. Hard grinding wheels are durable, but as a consequence they typically don't grind well as fresh abrasive isn't made available when working. Selecting a softer wheel of the correct grit makes a big difference, but it's easier to use a belt sander and that's why it's used almost exclusively in cutlery.
Sharp mower blades work a LOT better than dull ones, for cleaner cutting as well as plowing thru heavy stuff, so it's worth keeping the blade sharp. Since grass usually has lots of dirt in it blades dull quickly, mowing rocks doesn't help either, so check it often, sharpen as needed, and don't fret too much about angles and such. Just roughly follow the original angles, which will be large to minimize chipping. Mower blades aren't that expensive so having a spare that you keep sharpened makes for a quick change, and you can then ponder the technical challenges of sharpening the blade at your own leisure :^)