While the knife is dunked in warm water make sure to open & close the tools and blades to help dissolve salts in the nooks & crannies.

Just a personal bias on my part -- I hate using WD40 on knives. This is mostly because of the smell. My recommendation is to use a simple high-grade oil like 3-in-1 or similar. Of course you can also use the higher end stuff like Militec. Work it into the joints by opening & closing the tools and blades.

Don't forget while rinsing & oiling to get the joint on the scissors and - if you've got the newer model - remove the screwdriver bits from the holders.

You should be good to go.

Yeah, don't forget to rinse off the sheath real good too. Like Alex said, dry it before stowing the knife away.

Ken