This PLD in my dynamis LS went 1/7 on Attestation of Glory but now he has Excalibur. He had the currency for a long time too and the thing wouldn't drop.

Then I needed an Attestation of Glory for my PLD as well and went 1/2 on it. But now I need 2000 more shells to get Caliburn. Seems just totally random on the drop rates.