Like all La Vaule (S) NM Level 69 Weapons, you'll need the Supremacy Earring to get the full "Set:" effect. The earring drops from the BCNM that is granted access if you defeat all 8 NMs in La Vaule and trade the 100% StrongBox items in to a NPC Named Lurouillat in Southern San d'Oria (S).
Those items also benefit San d'Oria in Campaign. Look up the quest called "Sealed Containers."
Graciel is correct, except that the Strong Box items benefit the nation you turn the box into, not just San d'Oria regardless. The other NPC to turn them into are Pogigi at Windurst Waters (S) (G-9), and Kevan at Bastok Markets (S) (F-9).
