I have been trying for days and I have not been able to obtain it. it has a blue check mark on the image but I don't have it in my inventory or in the vault I have checked multiple times. I was wondering if anyone else was having this problem
In addition to Tuxydoh's reply; because they have a fixed roll of perks, ritual weapons like Null Composure can be pulled freely from collections unlike 99% of other Legendary weapons. So you may not have checked Collections due to that.