Bill often has sage things to say. In this case, though it sounds weird to use WD-40, it's entirely appropriate if you want to clean your knives with water. Because "WD" stands for Water Displacement. It's why the product was invented.
But why clean your knives with water to start with? I guess if they are really gunked up or full of dirt or something. I would think for pocket carry that just a bit of cleaning with cotton patches and maybe some oil or powder solvent, or similar would do the job. That's worked well on most of my Spydercos.
Several years ago I got all hyped up about the newest latest lube called Frog Lube. If you've read or watched videos, you'll recognize that Frog Lube really wants to be heated up quite hot as it's applied to parts so it can "soak into the metal". You are supposed to use a heat gun on the metal parts with the Frog Lube applied to them. So I took apart one of my Delicas, cleaned the heck out of it, and did the full Frog Lube treatment. It took several hours, including getting the reassembly just right. I was sort of proud of myself. Knife was nice and slick to open and the blade had a slightly slick (but not sticky) feel to it. I was impressed!
...until about a week later when it mostly wore off. Not exactly worth the time and trouble.
I say keep your knives assembled until there's a good reason. Like if you spot corrosion inside or something similar.
Brian.