It's a sword! It's a pickaxe! No! It's a PICKSWORD! A diamond pickaxe that is used as a sword aswell as a pickaxe!!!
It's useful for PVP! *clip of PVP* Opponent: "You're fighting with a PICKAXE???" You: "Yes. 1v1." *you deal alot of damage* Opponent: WOAH!!! How much damage does that pickaxe DEAL?!
It's useful for taking over the mine! Your worst enemy: "Hahaha! I got the first emerald!" You: "Well, I got the other 21 of them in 2 minutes!" Your worst enemy: "Wha-WHAT?! SAY WHAT?! You're so good at mining!" You: "I know I am!"
Works in singleplayer and multi-player.
Might not work in 1.7, 'cause I don't even know if command blocks EXISTED in 1.7!