A close observation of the grizzly head shows striations on the bevel where the grinding wheel did its job.
Our job in sharpening them is to keep the angle of the bevel the same. I will apply file pressure agressively at first until the scratches are gone from the bevel. Look carefully and you can see some of the roll or the bevel but most of it is on the other side.
I sometimes blacken this out with a magic marker to see where the file is doing its work. I will file the beveled side from front to back and the file will move out over the bevel away from the furrel until I can feel a burr starting to form on the back side.
Once the roll or burred edge is felt the agressive sharpening ceases and the weight of the file is virtually all you use to roll the edge back and forth until you have a razor sharp edge.
keep the file flat to the back. I believe the one sided bevel of the grizzly is what makes this broadhead so awesome. Look over the inside of an animal you shoot. I have seen damage like I never have seen with any other broadhead.