Sharp tools will last longer and work better.
I've been using the AccuSharp tool for 20 years to keep shovels, hoes, pruners and anything else with an edge sharp. Click on the link to find a store near you.
Some gardeners prefer to use a file or some other means to keep tools sharp.
I'm still using many of my grandparents tools and want them to last for as long as possible.
I didn't think much about sharpening my tools until I spoke to a group of sheet metal workers...not my normal crowd. I was a little nervous, but found them to love gardening and were real tool guys. They opened my eyes about keeping tools sharp.
There's a big difference in using a sharp shovel and a dull one.
For the wooden handles I coat them a couple times a year with boiled linseed oil to keep them happy. Those old ash handles are incredible and when treated right will last several lifetimes.
I also coat the metal parts with a little motor oil to retard rust.
In the tool shed is a five gallon bucket of play sand with a quart of motor oil added. Before I hang my tools back in the shed, I plunge the business end of the tool into the sand/oil mixture. The sand helps clean off any loose dirt and the oil will keep the metal from rusting.
Keeping tools in good shape will make gardening easier and will extend their life too.