BobP

Yes you can paint water based Createx directly onto a blade without a primer as long as your topcoat is durable enough.  I use a moisture cured urethane (Dick Nite S81) over Createx to paint spoons.  There are several ways to go, you need to choose a regimen of coatings that are durable and compatible with each other.  Take a look at the Dick Nite site.  He builds and sells spoons and also sells coatings to hobbyists.  He uses solvent based lacquers to paint his spoons and topcoats them with his own proprietary moisture cured urethane. 

I paint blades with water based airbrush paint and then topcoat them with a moisture cured urethane topcoat like Dick Nite S81 lurecoat.  It's the best topcoat for metal blades.