Have to finish on different settings
Using the Scarab Gun method, fly to the building that is cut in half. It is on one of the floors. Can shoot it about
2 Choices here
You have to do these on legendary mode
After you awaken, go straight ahead. There should be a passage in front of you and walls around you. Notice the ledges on the walls. Jump up them, then onto the roof. Go to the right (Not towards the skull) and go across that wall. Grenade jump to the top of that roof, go across to other side and get up that roof.
Then, follow the path.
Side note: If you see a hole on one of the roofs, fall into it to get a sword