I believe I would chisel out a diamond shaped area that includes the charred area and glue in a tightly fitted corresponding diamond shaped piece of wood. You are able to carefully choose a piece for grain flow and color. This solid piece can be shaped down to the original profile of the wrist, stained and finished to match then checkered.
Ok, looking back at the picture it wouldn’t be a diamond shape exactly. The process remains, just remove a shape to include the charred wood along checkering lines and make a piece the same shape to go back in. Pretty straight forward repair that would be as strong as the original.
That's the solution I would be trying. Could even go a little crazy and add a touch of palm swell there, just to be different.
Was someone bending the wood and let a heat lamp get too close? I could see that happening.