To reach this chest in the Nave of Notre-Dame, enter the room from the upper east exit.

From here, you need to time your swings across to the west side of the room to avoid the lasers.

Once there, hit the Lever to create a shortcut back to this point, then swing over to the far northeast corner. When you reach the anchor, use it to keep yourself in the air until the platform below has reappeared and the lasers are down.