I'm glad to see that you check the sharpness of your mechanical broadheads. I have to wonder how many others do. I too, also found that some of the Rage heads to be not as sharp as I like, and returned them. Do not know anything about the NAP "killzone". I'm not a fan of chisel tip broadheads. I prefer a cutting tip. NAP makes a "killzone" with a blade cutting tip. This will be my next purchase when I need more broadheads. I use a "Snyper" made by ROCKY MTN that is a mechanical that is much like a Rage with a cutting blade tip, but with a sharper blade. I was lucky enough to purchase several packets before they disappeared from the store shelves. I believe that the Rage people bought the Rocky Mtn Co. out. Cutting tip mechanicals can be resharpened. It's tedious, but it can be done. The side blades can be resharpened too. Anyway, I like the NAP "killzone", but with the cutting blade. Chisel tip or blade tip, it's just a matter of preference. You should do well.
never say never
patience is the companion of wisdom