When I worked on one of Son's Trompettes, I asked him if he would like to see a flat section near to the heel. He did, and I've made one, symmetric, some 19 degree per side, some two inches long. Normally French come with it, but they soon disappear with the common steeling.
I've tried a comparable flat section with a Misono Swedish Carbon. A symmetric section at some 16 degree per side for small, relatively rough tasks.
It allows me to keep a highly asymmetric edge of some 20 degree inclusive on the rest of the blade.