Dreeg’s Affliction: Includes +1 to Occultist Skills
Solael’s Decimation: Includes +1 to Occultist Skills
Bysmiel’s Domination: Does not include +1 to Occultist Skills
What do you have against the animal Witch God? 
To make this post serious, I find it surprising that Shaman (Primal Instinct) and Necromancer (Dirge of Arkovia) have pet relics that grant +1 to skills, and yet Occultist - which can use all the skill points it can get - does not have any such thing. Bysmiel’s Domination is an incredible relic slot for pets, especially for those that rely on temporary pets like Primal Spirit. The lack of skill bonuses, however, really takes away from it, especially compared to Mogdrogen’s Ardor that grants +1 to both skills.
Since each mastery has 3 relics. They’d need to axe one. Quite frankly I am willing to give up on Eldritch Pact, not because its a bad relic or anything. Just that as you say thematically it makes more sense to have Bysmiel’s relic grant us +1 to mastery skills
Since we’re on the topic of pet items, shadowfiend chord doesn’t have any bonuses to HP nor has any resistances.
I think plus 1 skill would be really ,like really nice to have, but the problem with this relic is that it’s effect is reactive instead of proactive———-You don’t need to trigger such powerful burst if you are facing packs of trash mobs. You want it against bosses and nemesis——but the summoner is fragile, imagine that you have to find some physical contact with some overpowered monsters first…:p:p
if you have lots of base pets, bysmiel is insanely powerful as is
As Sneaky Parrot said above, pet Cabalists aren’t exactly known for their tankiness, so while the pet bonuses are indeed amazing, the player does have to make the choice between going all-out on offense and being able to take enough hits for Bysmiel’s Domination to activate when you need it.
I see it being much more useful for players that take the Primordial + Order devotions to give themselves a lot more survivability while letting the relic help out a lot with offense. I see it more as a boon for players with a lot of temporary pets (regular Will of Bysmiel) as it helps them put in as many hits as possible before their return to their resting place.
Adding +1 to Shaman or Occultist on Bysmiel Domination would make Primal Instinct completely irrelevant, in my opinion, so developers will not do it.
I also think that Mogdrogen Ardor is best relic for pet builds in view of +1 to all skills and PERMANENT bonuses for all pets, without necessity to spam active skills (Primal Instinct) or necessity to be hit (Bysmiel Domination).
I think there is no best there.
For my cabalist skelemancer build, I was using Mogdrogen’s Ardor first, then changed it to Bysmiel. First I was very sad to leave +1 to all skills there but powers within Bysmiel relic is hugeeeee but again my skelies are dying so much at the wrong time where I needed them most so I changed to dirge of arkovia which I think it is best of both worlds for my skelemancer. While giving +1 to all necro, it also helps me summon the servant, which is the game changer for me, I think. ı can say that it is a reliable summon both in the offensive and defensive side.
Anyway, if Crate decides to change the Bysmiel as you said in the post, I probably would go that route. I really miss the ultimate power of Bysmiel but all-around part of dirge of arkovia is probably the best for my skelemancer for the time being.