The Code-4 uses AUS-8. It's a good blade steel, and Cold Steel does a great job with treating theirs. I don't have experience with the Code-4, but I do have an American Lawman (also AUS-8). It will take a very keen edge pretty easily (diamond stones, Sharpmaker, or even natural stones), and maintenance is also easy (few swipes on a leather strop or Sharpmaker). I haven't had issues with rust with any of my AUS-8 blades. When cutting very hard materials (eg. cutting a tin can apart), the edge can roll on you a bit. I haven't had any issues with chipping (other than once case where I accidentally dropped a knife on a concrete floor tip-first).