How do you get the sword in thing thing 4

you have to have 500 melee kills. when you reach 500, go to the next area and your pipe auto-changes to it. easiest way to get it is to stand by a teleporter and let 4 guys spawn, and then kill them all with the pipe. if you are playing a hacked version, you'll most likely one hit with the pipe/sword, making it much easier.