You will generally get a little more scale using a kiln because there's no fuel to burn up the oxygen like in a gas forge. You can put a small peice of charcoal in with the knife to help burn up some of the oxygen and it will help some. I mix up some very thin refractory cement like satanite and put a thin wash on the blade and that helps prevent scale too.
I like to just quench the cutting part of the blade, but lots of factory knives harden the whole knife and you don't see them breaking all the time. If you do a good draw after hardening, it should be fine either way.