When shaping out a graver, wether it's made from a lathe tool blank, a file or any other piece of decent steel,,
Carefull grind the cutting end down to a very small tip.
if you happen to gring it too far and make it a spike point, that's OK as you can then just take it back a small amt on a stone and there's your flat face again.
The idea is to have a very minimum of a 'face' on the tool.
That will make it very easy to keep sharp, fast to resharpen. Most importantly you will not be so inclined to round that smaller face over when sharpening as you will a larger area.
The heel on a flat graver bottom edge and the heel on each side of a V shape chisel need not be very long at all.
Just a very minimum of length, as this only redirects the point so that in cutting it makes the engraver raise the tool off the surface and keeps your hand and fingers clear of the work.
It also provides a stronger point of course and changing the angle in small increments is sometimes done just for that purpose.
An extreme 'high' heel is sometimes put on a graver in cutting some specialty work like silver ware where initials and monograms may be placed at the bottom of shallow bowles and the like. That keeps the graver upright to the extreme to avoid hitting the edges of the work piece while engraving deep down in.
A long heel can be helpfull in gun engraving to some when cutting very long straight lines like borders. The heel rides in the cut line and helps direct the cut.
Some find it helpful,,others not so much.
If you use a graver with a heel that is too long on general work,,you will get that raggety saw-tooth looking effect on the outside of arcs and circle lines. That's the long heel of the graver dragging behind damaging the cut line.
The tool needs 'lift' to clear the cut going around arcs and circles. A short heel with the proper angle will do that for you.