Arrow of Extrication (Quest)

Overview
Prerequisites: Completion of Turning a Blind Eye and XXXX gold fenced. Faction: Thieves Guild Quest giver: Gray Fox, via one of his messengers Methredhel or Amusei Reward:

Background Information
Amusei will meet you in a major city and ask you to meet the Gray Fox at ____ House in Chorrol. The Gray Fox wants you to steal the Arrow of Extrication from Fathis Aren's room in Castle Bravil.

Walkthrough
This is a long quest with many locks, so be sure you have plenty of Potions of Healing and lockpicks.

Head to Bravil and enter the castle. From the Great Hall, head up the stairs and into the Lord's Manor North Wing. Go down the hallway a bit and enter the first room on your left; this is Fathis Aren's room. You won't find the Arrow in his room, however, you may notice that there is a movable pillar straight across from the door you entered. Activate it and enter Bravil Wizard's Grotto.

The Grotto is a long winding set of tunnels and rooms that are filled with Conjurers, Mud Crabs and enemies scaled to your level (Spider Daedra, Frost Atronach, etc). Head straight ahead and you'll be confronted with Dremora Kynmarcher or Dremora Markynaz. Kill him and keep going straight through the gate. Follow the water-filled tunnel until you get to a deep pool of water. Kill the slaughterfish and swim down past a few rock ledges. If you look to your left (roughly north), you'll notice an opening in the wall. Swim through that and back onto land. Note: If you swim all the way down through the hole at the bottom, you'll come across a Giant Slaughterfish.

After this, follow the tunnels and rooms (there's only one main way) to the Bravil Wizard's Lair. You may come across more Conjurers, rats, or Dremora. In the Lair, here again it's one main way, follow the hallways and rooms, fighting or sneaking past Conjurers or other enemies. Before entering the door to Fathis Aren's Tower, save your game.

Once you enter the Tower, you will be met with multiple enemies including, but not limited to, Frost Atronach, Spider Daedra, Daedroth, and Fathis Aren himself, along with anything else he or the Daedra conjure, and often at the same time (again, the exact enemies depend on your level). Kill them all, fight your way to the top of the tower (fourth floor) where you'll find a small room with a chest that contains the Arrow of Extrication. Picklock the chest, take the arrow, and leave the tower. You can leave by fast travelling or by walking out the tower's large door, since you should have the key from Fathis's body. Return to the Gray Fox for your reward.