Thanks for the tips, I like the idea that their armour is better forged allowing them a 6+
FNP. Not sure the ulthwe stratagems and relics fit with the fluff so may just leave them out.
Yme-
Loc seems like a craftworld that could conceivably use any trait, providing its consistent across the army of course. Being a broken/newly repaired craftworld I suspect they would take wraith units, have some aspect warriors and leave most of their guardians (artisans) at home. Lots of fluff options really.
Don't want to be 'that guy' who just picks the best attribute for their army to win