On the vampire apparel there is a sort of compass rose. I've noticed it on some high-ranking vampires and their generic associates. Is this a symbol of their order or some sort of a stylized decoration? Am I just missing something completely? It's confused me since the release. (for reference http://uesp.net/wiki/File:SR-item-Vampire_Armor_Male_01.jpg)

Woooow....I've noticed that before but never really thought about it. Those are some great questions and thoughts....none of which I have an answer too.

My best guess however is that it is an emblem of Harkon's Order. I'll refrain from using "Volkihar" because honestly, I don't think he is one...but that's another thread Sooo, yea, kinda like the Dawnguard emblem they wear, but only for Harkon's Vamp Family.

My character's a right and just man. I really like the look of the vampire outfits, so would it be wrong to parade around their logo?

It's Molag Bal's symbol, which is the creator and patron deity of vampirism.

Actually, Molag Bal's symbol is skeletal-like and monstrous-looking.

Looks like the http://images3.wikia.nocookie.net/__cb20110402074806/warhammer40k/images/4/4a/Tzeentch_Icon_small.jpg from Warhammer 40k to me.

It does look like that star I think you have something there!

I don't think there is anything 'wrong' with it...but then again I am a nasty nasty vampire . It is a really nice look. It's your RP so you could justify it however you'd like and it would work, I think.
However, 'strictly lore' speaking, you'd fit better within a light set of Dawnguard Armor me thinks. I never really liked the light helmet, but I've killed seen several Dawnguard NPCs with all light armor and wearing the heavy helm...which looks really good. Or no helm is good too...or a hood of some sort would work as well

...but that's all just my opinion...

Pretty sure there is more then one symbol Molag Bal just like he has 2 different looking shrines.

And you know this for certain?

The strange part about it is that it looks a bit like the dawnguard icon.
http://fc03.deviantart.net/fs70/f/2012/191/4/f/the_dawnguard_by_zabuza318-d56o106.png

His symbol isn't a compass, though. It is more morbid and deathly looking. For example, the Mace of Molag Bal has the same symbol as Serana's collar and her emblem, same for Harkon's emblem, likewise for his altar in Markarth and in the Volkihar cathedral.

Also Molag Bal's stuff uses 60 and 120 degree angles, not the 90 degree angles in the symbol on the vamp outfits. I always figured that the Dawnguard had a stylized sun and the Vampires have a corresponding compass looking penannular that may represent needing to navigate at night, or when there is no sun.

This makes sense, especially the inverse relationships between the two opposing factions. I'd also like to add that the belt buckle on the vampire outfits has a similar design, albeit with less directions. It could just be a coincidence though. http://uesp.net/wiki/File:SR-item-Vampire_Robes_Male.jpg

His symbol could be many things. Every Daedra / Divine has several emblems or icons that represent them. Take Diabella for example. You have that naked statue, the type of flower depicted in that statue (not sure of its name), the shrine, and the amulet (which does take on the aspects of her shrine).

What I've found is this.
http://images3.wikia.nocookie.net/__cb20120612162149/elderscrolls/images/e/e2/Dawnguardvampiremaster.png is a shot of Harkon. His broach bares the face of the bloody shrine in the cathedral.
The bloody shrine is a take on the vanilla version of the shrine in Markarth as seen http://images4.wikia.nocookie.net/__cb20120513042927/elderscrolls/images/c/cc/Molag_bal_mace_altar_rusty.png.
The mace also bears the face of the shrine as seen http://images.wikia.com/elderscrolls/ru/images/e/ec/Mace_of_Molag_Bal.png. But also notice the spiked edges of the mace and shrine.
I think those spikes carry over nicely to the broaches worn by Serana http://skyrim.nexusmods.com/Images/1207799-1345615689.jpg, the Vampire Royal Armor http://www.skyrimdl.com/wp-content/uploads/2012/08/Dawnguard-Vampire-Armors-Mod-at-Skyrim-DL.jpg, and the Vampire Armor http://static.skyrim.nexusmods.com/mods/images/21637-3-1344048558.jpg. Obviously these broaches are a take on the chaos symbol ( ) but it still could be (and imo is) another symbol of Molag Bal.

Interestingly enough, that star symbol could also be a perversion of the Dawnguard's sun / light symbol, though I couldn't find any 'good' link to an image...but we'll go with https://images.nonexiste.net/popular/wp-content/uploads/2012/08/The-Dawnguard-heavy-armor-set-looks-amazing.jpeg for now.

[Edit] Another thing just occurred to me. Take another look at the Vampire Royal armor worn by Serana (and you, same thing). Notice that her collar has a similar demon-skull look as her fathers broach, and the shrines. It could also be that the Royal Armor is an 'artistic transition' deliberately developed by Beth to indicate a transition from one emblem to the other, yet maintain the continuity of their symbolism. Perhaps a little deep, but I find it interesting nonetheless.

Nice. So it's probably just another incarnation of the chaos star in a video game. What about the buckle, irrelevant?

Another thing I thought of is that the Vampire penannular has what looks like http://imageshack.us/a/img266/6098/penannular1.jpg in it which may just be a reference to the theme in the DLC.

The buckles are irrelevant. I just saw them on ordinary clothes.

Not necessarily irrelevant. They were likely influenced with everything else in mind, just kept subdued to keep in theme with the robe designs. That's my thought anyway, only because its kind of a random design, a loop with four prongs. Too random, imo, not to have anything to do with the other

That's a good thought. I can see that The theme you refer to, I assume, is Auriel's Bow.

Aye, shooting the sun with an arrow. It doesn't make any logical sense from within the game, since it's probably not likely that the Vampires would adopt this symbol across the board because of Harkon's obsession (even random Vampires in the wilderness now wear the vampire armor), but from a game design perspective maybe someone thought it would be an appropriate motif?

I agree with that

I just think it's the new Symbol for Vampires in general. The Vampire Royal Armour has the Molag Bal deathly looking symbol on the uhh... right shoulder thing, and the Females have it on the neck brace thing. The Female one also has the Vampire Symbol on the right shoulder (I think) too, so I've come up with aTheory that the people with Royal Armour and that Molag Bal Symbol could be direct decendants, or decendants of Vampires with Molag Bal's gift (Vampire Lord Vampires), and the other Vampires with the Vampire Armour with the Star Shaped Symbol (what I believe is just the new Vampire Symbol) are just showing off that they're Vampires.

The Female Royal Vampire armour has that star shaped Symbol on it, as they do the Molag Bal one, which could possibly just be saying that, "Hey, I've got the Vampire Lord powers from Molag Bal, I'm a Vampire and proud, so I'm gonna wear both of these flashy Badges!"