Legendary armors are supposed to have a +2 increase to damage and energy resistance.
For reference see e.g.: mod_Legendary_Armor_Charisma_and_Intelligence "Sharp" [OMOD:001CF57D]
-> ADD DamageTypeValue dtEnergy [DMGT:00060A81] 2.000000 for the energy resistance increase
The legendary armor effects from the Far Harbor DLC are missing the energy resistance increase.
Affected Object Modifications:
dlc03_mod_Legendary_Armor_ChanceToBurnMeleeAttacker "Incendiary" [OMOD:030107AE]
dlc03_mod_Legendary_Armor_ChanceToFreezeMeleeAttacker "Cryogenic" [OMOD:030107AF]
dlc03_mod_Legendary_Armor_GettingMeleedTriggersInvisibility "Cloaking" [OMOD:030107B0]
DLC03_mod_Legendary_Armor_LowHealthIncreasesStats "Unyielding" [OMOD:03010BB5]
dlc03_mod_Legendary_Armor_LowHealthTriggersStimpak "Auto Stim" [OMOD:0300F5BC]
DLC03_mod_Legendary_Armor_RadsIncreaseStrength "Rad Powered" [OMOD:03010B86]
See attachment for a fix.
Atom's Bulwark and Acadia's Shield are fine.