As for sharpening, see Lee’s book on sharpening. Also, Mike Wenzloff writes
Due to the shape of what would be called the bevel, they are easiest to sharpen
either with the side of a grinding wheel (light pressure) or by using a stone
set near the edge of the bench and the chisel's "bevel" oriented so the handle
is over the edge.
A swan neck chisel (or, lock mortise chisel) doesn't need a high degree of
sharpness. It is a scraping tool designed for cleaning out bottoms of mortises.
I usually leave it as is off the grinder.
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