Damascus is the generic term for two different types of steel (or sometimes steel and another metal) forged together in a special process. The process involves folding the two steels several times and then etching it to bring out the pattern created by the folding. The bladesteel in the C01 Worker from the Evolution edition of workers is a damascus steel made by Tim Zowada.
In his own words:
I made the steel for the Evolution edition. The steel was sent to Japan for blanking, grinding and heat treating. The steel was a lamination of W2 and ASTM203E.
Ed Schempp also created a Spyderco Bug patterned Damascus for the bolsters of the C76 25th Anniversary Delica.