Left 4 Dead Console Command Oddities?

I'm just very curious to a few things. Now, when you are in the home menu, you can press the "~" key and it will bring up the console command. When it's up in the main menu, you can type in "map (name of the level/map you want to play)" and it will create a single player server that allows you to then open command console in the game and cheat. ("sv_cheats 1") But when you are the survivor and you type "give (name of item you want)", a few odd things come up. These odd things are: boomer claw, charger claw, hunter claw, jockey claw, smoker claw, spitter claw and tank claw. So, i thought 'well. this might be fun.' but when i tried to spawn this item, i regular, first-class pistol drops in front of me and it glows blue but even if you have a melee weapon, you can't pick it up. So, does anybody know what these are and/or what they do?