Some clear improvements.

Dress Down is a like a blue wrath that's proven itself in cEDH. Omen of the Sea is a perfectly acceptable card, but I think Dress Down is going to be a much higher pick.

Fell Stinger is much more efficient than Coffin Queen and better at attacking.

Nightmare Shepherd has tested poorly for my group since players tend to want to recur the same creature more than once, rather than exiling it. Pitiless Plunderer is much better in aristocrats shells - so much so that I considered not adding it to avoid combo shenanigans. But I want to power up the BW aristocrat decks like Teysa Karlov, and it does that.

I was skeptical of Ragavan in this cube environment, but it's great in cEDH and after some testing I'm happy with it here.

Heat Shimmer is what Twinflame wishes it was.

Fairly big change to my Orzhov section because Kaya and Blot Out the Sky ended up underperforming. Kaya was fine but didn't do enough, whereas I'm basically always happy to draw Talisman of Hierarchy. I never ended up casting Blot Out the Sky. In part that's because in the decks where I could play it, I found that I had a lot of artifacts and enchantments that I didn't want to destroy - and I wasn't interested in only creating a few 2/1 fliers. On the other hand while I've been skeptical of Athreos in the past, it has tested fine and I've been happy to draw it. In this case, Talisman and Athreos provide what BW decks want much better than the two cards they're replacing.

Koma is a fine card, and while I thought it would slow games down I've found in testing it tends to be better to keep the coils than tap things down. That said, I think Aesi is better.

Bazaar of Baghdad is worth mention because it's effectively power. For a long time I didn't add it because it has low numbers on EDHRec, and I assumed that reflected narrowness. But recently I learned it might just reflect the difficulty of getting one, because a number of commanders can use the effect. Then I had to test it to see if it would break my cube, and I think it's been fine. It's a powerful card, but I think my cube is a match for it.