Outskirts Energy Sword
From Halopedia, the Halo wiki
In the Halo 2 Outskirts (Level), there is a hidden Energy Sword in the top level of a building not far from Hotel Zanzibar. The building's roof has a large chunk missing, suggesting something hit it. The sword is imbedded in the floor, next to a arrangement of rocks that spell out Rex and blood stains. While many claim it to be the only sword in the level, any SpecOps (and others) Elite may draw a sword if you get close.
WARNING!: Getting this Energy Sword will cause a white-clad Elite to attack Hotel Zanzibar (if you have not already killed the enemies there).
Directions
To reach the sword, one must get to The Rooftops Vacation. This can be acomplished at the very start of the level. As soon as you exit the room with the crashed Pelican, jump onto the door frame. From there, jump onto the higher platform. It should be noted that the Blind Skull is nearby. It might be wise to bring a Sniper Rifle in case Covenant bother you. Make your way over the rooftops to the sword.
