As said, the designation hardwood vs softwood isn't about with hardness of the wood. There are hard softwoods, and soft hardwoods.
Most conifers ( softwoods) don't make the best handles because the way the wood grain is formed allows wear and makes it soft. You can do things to the wood to make it harder, but the wood is still a pretty plain wood. Stabilizing or a hard finish worked into the surface will help.
The heart of some of these is much harder, and would last longer, but the heart also is much higher in pitch, and may present problems as a handle.
That said, I have made knife handles out of softwoods from The Ocean View Roller Coaster ( fir), Harrison's Pier ( cypress ), and The Duck Inn ( pine). All were local landmarks, and they are gone now. I had the wood stabilized.
Other softer woods I have used (stabilized) are holly, sycamore, and birch. Some of these are stunning.