Dear Moron
Just thinking about it (I've got my good clothes on so I'm not going to test this theory) what about this? Taper a piece of round rod (size depends on size of feather) to a long point. Turn end for end and neck over the edge of the anvil at about the right length of the feather. Rotate back and forth through only 90 degrees when you're necking. That will put a thin square section on the side of the rod. Hold the stalk so this squre section is in the middle of the rod as you look down onto it. Flatten the feather bit so it is fat through the middle and thin on the edges. Now make a top and bottom swage with a thin groove along each face. Pass the feather through the swages to get a ridge along the length of the feather. It will be difficult to get a nice flowing line. I'll leave that for the next bloke. If this doesn't work try something else!