The Balance of Power questline artifact appearance rewards are now account-wide. After unlocking the base appearance, the criteria for additional color variants (such as the Glory of the Legion Hero and Unleashed Monstrosities achievements) may be completed on any character to earn the appearances.
Enjoy! I know my alts will. xD
Awesome. Not sure who I have competed that on, assume it will just Auto Unlock!
More Artefact appearances I’m never going to use 
YESSSS.
BoP was a PAIN to do on all chars! Thank you Blizzard so much!!
does it matter if you finish the questline now or after the update?
Excellent - there’s a weapon appearance I want for my Hunter that’s locked behind Balance of Power and I couldn’t be bothered to do it a second time.
Good news, apart from the fact that I’ll actually have to do it now - i had a good excuse not to do it before…
About time. It’s a nightmare to do this multiple times.
SO you are saying when i did my druid balance of power i will have balance of power unlocked on my alts without doing that questline 3rd time?
Yes, Correct
Now that is a good QnL change for the game 
Have you tested it on the PTR and that’s definitely how it works? The wording of the blue post is somewhat ambiguous. It could mean the entire quest chain is account wide, but it could also mean you still have to complete the quest chain on alts but can unlock the remaining 3 colour variations on any character.
EDIT: I’ve just checked on one of my characters that only has the base artifact (and colour variations) unlocked on live, and she still only has the same on the PTR.
Base only , you have to earn the other 3 per class . So for example i think 8 world bosses ? and clear all dungeons on normal if i recall.
That’s the opposite of what it says in the post that’s linked in the OP.
For reference, it says:
After unlocking the base appearance, the criteria for additional color variants (such as the Glory of the Legion Hero and Unleashed Monstrosities achievements) may be completed on any character to earn the appearances.
And, as I stated, I don’t have the base Balance of Power appearance unlocked on the PTR on a character who hasn’t completed Balance of Power. I DO have the base artifact appearance. (For example, on my protection paladin, I have all 4 colour variations of Truthguard, but no Divine Protector, which is the Balance of Power appearance even though I’ve completed Balance of Power on my druid.)
Oh that sucks then and will dissapoint lots of people 
Good news. I tried importing the druid and logging in on the PTR in case it wasn’t connecting directly to my account data, and it turns out that was the problem.
My paladin now has all the same versions of the Balance of Power artifact as my druid has. So it should work fine when it comes to live, but my guess is that it probably won’t work until you’ve logged in with the character that originally did the quest chain.
Thank so very much for checking that out really made me smile 
I’m honestly amazed that it’s taken so long for them to do it. It should have been account wide from BfA pre-patch.
Totally agree . I mean its a good questline but doing it for all the classes lol no thanks