How to sharpen black talon 2

[ZtCubster]

So i recently got a cold steel black talon and i know its designed for self defense but i use it for utility. Its chisel edged and i can't figure out to put a razor edge on it. i can put a decent edge but nothing spectacular like i can on other recurves. when i sharpen it, i mark it with a sharpie and the stone hits the top portion of the bevel and the edge but the marker stays in the middle of the bevel , almost like concaved. I've tried putting it on a mouse pad and sandpaper wrapped around something cylinder and i still have the same issue.

 

[Alberta Ed]

A diamond coated rod should work well. That's what I use to touch up my kukri.