The skin adds brass knucles to the knife.
Reskinned Allied Knife for DOD:S cause the standard skin is fairly boring.
Unzip the amerk.vtf and amerk.vmt files into:
C:Program FilesValveSteamSteamAppsYOUR USER ACCOUNTday of defeat sourcedodmaterialsmodelsweaponsv_modelsamerk
This is only the V_Model so it will be only visible to you.
If I get time soon I'll knock up the W_Model as well.
Just look for WARPIG on the GameArena or Internode 32 player servers :P