Shadow Trews  

The Shadow Trews are good intermediary BLM nuking pants, for when you've reasonably maxed out the INT and skill in the other slots and need MAB boost, but don't have Morrigan's Slops yet.

You get the Hadean Abjuration: Legs for this in Einherjar in the armory crate after you defeat all the enemies in your chamber.

You need Cursed Trews and the Abjuration to get this.

The recipe for Cursed Trews is as follow:
-Earth Crystal

*Velvet Clothx2
*Imperial Silk Clothx2
*Marid Leatherx1
*Nethercant Chainx1
*Platinum Silkx1

the entire Shadow Coat Set gives these stats in all:

* Defense +109
* MP
* INT +5
* MND +5
* CHR +5
* Magic Accuracy +24
* Magic Attack Bonus +4
* Enmity -12
* Physical Damage Taken +12%
* Magic Damage Taken -3%
* Damage Taken +4%

For more information on Einherjar go to http://wiki.ffxiclopedia.org/Main_Page

Good luck on getting it :)