This is how to find the rex energy sword on outskirts. It has limited energy, and is like any other sword, except that when you find it, it is sticking in the ground.
After you start the level, go to the hallway where you see the first grunt. You will see a light in front of you. Step on the light and crouch jump to the slanted roof. Turn around and you should see a pathway to the right, opposite of the lights. Go there until you reach the invisible wall. Grenade jump to the top of the wreckage. Go right and jump on the red roof. Go to the pathway on the right and jump over the barrier. You will now be on a roof near where the pelican arrives and picks up sergeant Johnson. I front of you will see a higher roof. Go near it, and grenade jump up to the roof. Go on the air vents and jump on the next roof. Turn left and you will see a hole in the roof. Fall in it and turn left. You will see it sticking out of the ground, stuck in the word REX written in blood.
Scarab Gun
This is how to get the almighty Scarab Gun!
IN METROPOLIS ONLY! Get into the tank and move along the bridge destroying everything in your way. When you reach the point where Cortana says "Nice welcoming party," do not shoot the Banshees that start on the way from the city. Instead, get out of the tank and start walking into the tunnel (you may take a Ghost if desired). Start moving into the tunnel slowly, pop one or two shots into one or two of the Banshees to get them to attack and follow you. The Banshee should enter the tunnel and will follow you. Do not board the Banshee, as it will explode as soon as you take it over. Continue through the tunnel until you reach the first gate. Get out of the Ghost if you used one. Walk up the ramp, take out the enemies, and lure the Banshee between the gates in the tunnel. This may take some time as the Banshee will try to follow you over the ramp on the right hand side. Proceed by walking until you reach the next gate and repeat the process to get the Banshee through the gate. Keep walking until you reach the very end of the tunnel. Kill the enemies so you do not get shot during this part. Shoot off the Gravity Pods (glowing pods on the wings) and either get the Banshee to follow you into the reddish room or melee the Banshee into the room. Go through the room and look at the tunnel leading outside. Get the Banshee to go towards the tunnel and board it as it enters. Note: Make sure that when you finish boarding the Banshee the "Loading...Done" message appears on the left side. If you do not board it at that moment, the Banshee will explode. Next, fly out of the tunnel and go immediately to the left. Notice the long bridge between the two buildings on the left. This bridge is very high up. After reaching the bridge between the buildings, fly or get out then walk to about the middle of it. There will be what appears to be a plasma rifle on top of a red triangle with a "!" on it. Pick up the rifle, get back into the Banshee, and fly back down where you are supposed to be. You now have the Scarab gun. It has unequaled range, unlimited ammunition, and will never overheat.
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