Currently Retribution Aura have this effect who buffs the damage of the party members by 5% when triggered.
This currently affects the Entirety of the Player Damage, and the damage of the primary pet given that they are also affected by the Retribution Aura.
Sadly, different from the primary Pet, Guardian Type Pets (Wild Imps, Dreadstalkers, Ghouls, Gargoyles, Mindbender, and many others) does not benefit from the aura and cannot gain the effect from https://www.wowhead.com/spell=404996/retribution-aura.
This is a considerable demerit for classes who heavily depend on Guardian Pets as its main source of damage like Demonology Warlocks and Unholy Death Knights as suddenly they only partially benefit from Retribution Aura, while specs without Guardians fully benefit of the 5% damage increase.
There are two ways this can be fixed, the first one would be to give a solution similar to the one employed to prescience from aug.evokers, and make the Retribution Aura replicate on every guardian, but this could cause potential issues related to lag as you would be replicating the effect on 20-30 pets per Demo Lock/Unholy DK in Raid .
The Easier solution would be to use the effects present in the Mastery from both specs, and apply the Guardian Pet Damage modifier(Aura 531) in the Retribution Aura Damage Buff
OBS: Given the primary pet is already affected by Retribution Aura, adding the Primary Pet Damage Modifier(Aura 429) won’t be necessary as this would cause them to double-dip from the effect.