Commander Zavala — In Rides a Pale Horse

"Guardian, there's something I'd like you to retrieve from the Vanguard vault. We've been storing certain high-value weapons here since losing our vaults during the Red War. The Cabal seek to destroy us with the Almighty. I want to send them a message, and I have the perfect delivery method. Take this keycard to the vault."

Before you can take the keycard, Zavala pulls it back.

"You'll have to go through my office to access it. I normally do not allow Guardians in there, so I'm trusting you not to disrupt any of my… personal effects. Grab the weapon and come back to me."