The Shedu is a secret weapon that was added to Warframe in the Empyrean update. Taking the form of an Arm Cannon, the gun encompasses the entire arm of a Warframe, and sit upon their shoulder. The weapon does not need ammo and instead will recharge ammo when not being fired. It fires a beam that does Heat damage and causes area-of-effect Electric damage upon impact.
To get the Shedu, you will need to complete the hidden Erra quest.
How to Start the Erra Quest
The Erra quest can only be accessed after you do a particular action in a Railjack mission. The first thing you will need is a Paracesis weapon, which can be obtained from the Chimera Prologue quest. To start the Chimera Prologue, you need to have completed The Sacrifice, and then visit your quarters in the Orbiter.
You will need to bring the Paracesis to the Veil Proxima on the Empyrean missions Star Chart. You will need to have one of the Intrinsics skill trees at Rank 7 to access this area.
A Sentient ship will appear on one of the nodes in Veil Promima for 30 minutes at a time and will be marked by a flashing red symbol. You will need to find and board this ship, then track down a red crystal that it houses. If you destroy the crystal with a Paracesis, you will be able to access the Erra quest from your quarters on the Orbiter. The mini-quest plays out in some cutscenes, and when they are over, you will have a blueprint for the Shedu.
You will also need to farm the following parts:
These parts can drop from Symbilysts that are found on the Sentient Ship in the Veil Proxima. To find the Sentient Ship, we would suggest using the timer on the Semlar website. When you have farmed all the pieces, you can build the Shedu in your Foundry. It has a 24 hour build time, which can be skipped for 35 Platinum, Warframe’s premium currency.