Haven't done terribly many knife handles, but I've worked with wood quite a bit, and used linseed oil often. Used it on tool handles quite a bit as a preservative. My best luck has been a generous coat allowed to soak for a while, then wiped dry and left overnight. Repeat daily for a few days if you want to be thorough. Top it with some paste wax if you want to be that much more thorough.
I agree with those who say that you should NOT let a wet coat of linseed oil dry; you will indeed get a sticky mess.
I agree less with the warnings about not over saturating the wood, but I don't know that I would be making a knife or tool handle out of anything all that porous, so maybe that is why I haven't seen the problem.
I have used Tru-oil and like what I got from it. Again, I haven't had that much experience with knife handles, but why wouldn't a finish suitable for gunstocks be suitable for knife handles? Both items need an attractive finish that will hold up with outdoor use.
Somebody pointed out that you have to be careful of rags that have drying oils (linseed oil, tung oil) on them. That is true, and worth emphasizing. As the oils cure, heat is produced. You get a big wad of rags in your trash can where the heat can't dissipate, and you can end up with a fire. My solution is to toss them in the charcoal grill and put the lid on. When I get enough of them to make it worth fooling with I transfer to the fire pit and burn them.
Same thing can happen with epoxy, by the way. You run into it when mixing larger quantities, like if you are fiberglassing a plywood boat. Mix up a pint of epoxy and you have to use it pretty promptly; if you leave it in the mixing cup too long it might start to bubble and smoke. Probably wouldn't run into that with the small quantities that you use in knife work, but it is worth being mindful of, particularly if you make a big mess sometime and end up with a bunch of rags with uncured epoxy on them.
I can't buy in to the idea that you should only use stabilized wood or a species that doesn't need a finish. That leaves out a lot of very attractive wood species. I have a lot of carpentry tools used on jobsites and yard tools used outdoors that see a lot more sweat and dirt and rainwater than most knives do, and if I hit them with linseed oil a couple of times a year they last indefinitely. And actually look pretty good too. Obviously a matter of taste, but a lot of the stabilized wood that I see looks kind of plastic to me. Of course synthetic materials have their place. And I realize there are some types of wood that are not mechanically sound unless they are soaked in plastic. It definitely IS a matter of taste, and I don't mean to criticize what another fellow finds attractive.
