Oh, sadly it's a vanguard weapon from the dark below expansion so it is currently unobtainable. I think there is a small chance you can still get vanilla and dark below weapons by grinding the corresponding strike playlist since the engrams you get are from that time period and have a chance to turn into legendary items. It is unconfirmed if this is possible so I'm not sure if there's anyway you can get weapons like the LDR anymore. However her benevolence, the queens sniper is very good and is similar.

Go back in time.