Here on the farm we use boiled linseed oil for tool handles. The benefit is that with this finish, the wood is still porous and when your hands sweat, the wood will still soak up the sweat. If the finish sat on top of the wood or sealed the pores, the water/salt from your sweat would build up between your hands and the handle and you will get blisters. We apply it by lightly sanding the handles with 220 sandpaper to clean off any accumulation of dirt or grime, then lightly apply a coat of boiled linseed oil with a cotton cloth. Once we get through the tools we’re working on, we go back and wipe the handles off with a clean cotton cloth.
Linseed is made from flax. You can get unboiled or regular linseed oil, which is marketed as Flaxseed Oil from many health food stores. I get mine from Puritan’s Pride online store because they run “buy two, get three free” sales every so often. Flaxseed Oil is approved by the FDA as a food additive and it also works well as a finish on any wooden surface food will come in contact with. I use it on cutting boards and an antique baking table we own.