The Back Way
Banshee-44 wants to give you a weapon stored in his workshop, but he didn't specify how to get in.
Locate the hidden entrance to Banshee's workshop and find the weapon.
"Banshee said Cayde knew about some secret entrance. If it were up to me, I'd say we should start looking in the Hangar. It's where Cayde spent all his time." —Ghost