Skulls in the Halo series have always required players to take some interesting routes to reach them. That being said, with Halo Infinite moving to an open world style of gameplay, that allows Skulls to be even more hidden. When equipped, the Blind Skull will remove all HUD elements and your weapons, so you are essentially shooting blind. Here is where you can find the Blind Skull in Halo Infinite.
The Blind Skull is located in the open world of Halo Infinite, not in any missions, so you do not have to worry about missing it. In the bottom left corner of the map is a mountain that has been split in two. Go there and jump on the western side.
Down in the split, there will be a rock shooting out from the west side that has the corpse of a soldier, a chair, and a few blue glowsticks. As soon as you get close to this soldier, an enemy ship will fly above you and take some shots. Just hide in the rocks behind you, and it will pass.
After the ship leaves, look down below, and you will see another soldier and glowsticks. Jump to them.
Turn around from that soldier, and you will see another glowstick.
Look down and to the left to see some glowsticks next to a wall.
When staring at the wall, turn left and walk to the edge to see more glowsticks against a wall back across the ravine.
Grappleshot over there to find the Blind Skull in the corner to the left.