Not sure if anyone has found this already but i have not seen anything on its location yet. Right before the room where you fight saber, before you drop down, on the right there are two vent grates to be shot out. Take the first one, ghost inside. Update: Just heard about another. If you play through Cayde's stash all the way to the end, in the room where you fight that boss. jump on the largest center platform and look left and down. It should be below you on the railing. It may blend in with the other lights on the railing, just be careful not to fall.