There is no Wand specialization Rune.
Afaik, wand specialization that should apply would be corresponding to the type of damage dealt by the wand. So if my wand deals fire damage, the go-to ring rune would be Fire Specialization.
Problem: I can’t use specializations other than holy/shadow while playing Priest, for example.
Fix?
I mean, really ?
Yes, some of us play specs other than dps, and for priest healers, wand is an important source of damage.
Check discipline talents, first line is a talent for increased Wand damage. Should be a hint 
Yeah but it’s good for leveling, you don’t need wand at max level. At least not enough to ask for a rune on rings…
I don’t play shadow. The same way you don’t play healer. I don’t like it, the same you don’t like to… not play dps.
So should I just be hindered when doing quests, for example? Should I be forced to play Shadow?
I have dual spec. Disc PvE and Disc PvP.
Should I be forced to forego one of my specs to be able to quest? And don’t get me wrong, I am used to questing in healing spec. I know it’s slower than doing it in dps spec, and I’m ok with it. But what is the harm in allowing Fire specialization to be used by Priests?
We have literally zero Fire dealing spells, it’s not like getting access to Fire Specialization would all of a sudden make Priests be broken.
Or, alternatively, include Wand specialization in one of the ring runes (ranged weapon spec for example), or just make one.
And to be honest, if they have the time to make changes to materials for a crafted bag, I think they can find a few minutes to include Wand specialization in a rune.