Folders: Mineral Oil if I want to add something protective. Also pretty good for the joints, but not as good as "hi tech lubes". For sticky or stubborn stuff, 90% isopropyl alcohol or Goo Gone. The later is especially good for tape residue.
Kitchen blades: Pretty much just soap and water, though every now and then I need a powdered cleanser like Bon Ami or Bar Keeper's Friend. BKF of course is highly regarded for it's ability to remove rust and secondarily for cleaning metal swarf from stones, diamond plates, and ceramics (like the SharpMaker).
Brian.