Instructions
Take an Energy Sword from a fallen Elite in the campaign mode of "Halo 3." In several levels of the story mode, a small group of Elites will fight alongside Master Chief and the Arbiter. If one of your alien allies dies in combat, he may drop an Energy Sword.
Study the multiplayer maps by starting a match alone. Explore and memorize the weapon layout of the maps so you can make a beeline to the coveted sword before your opponents when you play a real match. For example, in the Forerunner-themed level Construct, an Energy Sword is sitting on the south end of the top floor.
Place Energy Swords anywhere you want in any of the multiplayer levels by using the Forge mode. Forge allows you to set and remove weapons, scenery and items as you desire to make multiplayer more entertaining. Pick the Energy Sword from the "Weapons" sub-menu and place swords on the map by pressing the "A" button while playing as the Forge editor.