While it's true any knife sharpened on one side and not on the other could be called "monoedged", in this case what is being implied is a blade with an edge that is one molocule thick and incredibly sharp. The blade does of course get dulled with use, but the scabbard it is kept in resharpens it with every unsheathing.
Melee: Attacks with this trait can be used during close combat without penalty.
Penetrating: When a weapon with this trait successfully hits, it has D3 Armor Penetration against the target.