For WoW: TWW
On this character, I have the heirloom Devout Aurastone Hammer. I purchased the Runed-Ice Dirk for the matching T2 Priest outfit. When I visit the transmog npc in Stormwind, or attempt to use the transmog option on my mount, I only have the option of transmogging to other 1h maces or Legion weapons – nothing else.
Despite the fact that Priests can wield Dagger. What am I doing wrong or is this a bug?
Did you equip the dagger to unlock the appearance?
Don’t need to because I purchased the Runed-Ice Dirk which is a cosmetic item only from the vendor in Tanaris.
I can see the Runed-Ice Dirk in my appearances tab. But when I visit the transmog npc or use the transmog option on my mount, I only see two options: 1h mace and Legion weapons. I should also be able to see Staff, Wands and Daggers.
What I mean to say is, it’s a cosmetic item so did you use it to unlock the appearance?
Yes, I did. 
Daggers are currently unique in respect to transmog. They can only be mogged over OR to other daggers and of course the Legion Artifact.
It’s likely now that I think of it because they can only transmog into daggers.
Going to be honest and say that I am not entirely sure that I understand what you are telling me. It’s been a long time since I’ve returned to retail. Can you please elaborate?
Edit:
So… Daggers can only transmog to Daggers? and 1h Mace can only be transmogged to 1h Mace? I just played around with this… and found out. It doesn’t make sense to me because 1h Mace can be transmogged to 1h Sword. I know this because I was able to do so on my DK.
My apologies for the confusion.
Daggers have unique animations and due to this Blizzard has restricted their ability to transmog. You can transmog a dagger appearance over another dagger, but that is all that a dagger appearance can mog over.
Yes, if your class supports a variety of weapons then you would have more choices for which ones you can use for transmog. Such as maces. axes, and swords being interchangeable.
However, daggers cannot go over other weapon types due to their unique animation.
Oh wow. RIP. Ugh. Ok. Thank you so much for your help. I will just see if I can get a Dagger later on in game then.
Yeah, stabby stabby animations don’t mix well with maces.
I don’t know how new this is, but wands can now be transmogged to 1h you are qualified to use. I’m now going for wands for my mages, priests and warlocks. Minor detail: you aren’t allowed to shoot a wand if it is transmogged to something else like a sword/dagger/mace.