Commands on Tools

There could be a block (gotten with /give) that applies commands onto tools and weapons. Then if an entity capable of using that command is hit, then they will run the command. The possibilities are endless. Instant kill swords, battles where hitting the opponent summons lightning on them, command usage anywhere you want without going into chat. Of course this is only useful in certain circumstances but it would be really fun to use and could be useful on servers for admins or certain minigames. On top of that, you have to go out of your way to use this feature so if you don't like it, you never have to use it.