You should also look into single point diamond turning, diamond ultra
precision machining, or micromachining. Depending upon the structure of what
you are looking to fabricate, this will probably be the best method. With
single point diamond turning, in a fly cutting fashion, you can realize very
high aspect ratio structures with nanoscale level sharpness. Diamond turning
is also a very replication friendly process, that can allow for
electroforming of nickel "fathers" to copy the original "master" part, which
can be copied as "daughters" successively until the part wears. It is a
process good for both prototypes and mass production.

Silicon KOH etching may work too, but you'll be restricted in the geometry
of your blade, which may be a disadvantage.

David Casale