Sharpen them as you know how,,the one thing to do for gravers to be used expressly for cutting soft metals (brass, copper, gold, silver, etc) is to reduce the included angle of the face of the graver.
For most steel cutting, that face angle is generally anywhere from 45* to 55* included angle.
Everyone has their own preference and the type of steel can demand a change as well.
Cutting CRS and 12L14 is different than a difficult project like a Ruger#1 or Win21.
The soft metal cut very smoothly and clean with a much lower face angle. You will feel it when you cut either hammer & chisel or by hand graver.
Also the heel placed on the graver point doesn't need to be as long as that usually placed on the graver used for steel. It shouldn't be very long anyway as too long and the heel will drag around curves leaving the saw-tooth look on the outside of the arcs.
But a very slight heel will give less 'drag' on the soft metal as they can be somewhat sticky for lack of a better word when cutting them.
No need for an extra strong point in the soft metals, so no need as well for a large/long heel to strengthen the point.
Many engravers use a graver lube when cutting soft metals and it does help a lot.
It's mainly a Jewelry Engravers thing to use a graver lube, working on gold, silver, etc.
When I started engraving, Wintergreen oil was a common on the bench a graver lube. Worked well.
A bottle cap inverted with a cotton ball in it dampened with a couple of drops. Touch the point to the cotton then wipe it off(!),,that was enough for use.
I hardly ever use any graver lube anymore, but find myself wondering if I might try it again when working on some soft metal pieces in gold and the drag on the graver is definetly there.
