The Shado-Pan have the “Omnia” discipline, which seems to include arcane mages as well als priestly skills with Light and possibly Void, I guess? But the information is very, very scarce.
The Omnia discipline is led by Master Yalia Sagewhisper. They are charged with maintaining the wisdom, knowledge, and sacred traditions of the order. Classes known to be in this discipline include priests and mages. Omnia Mages can be found in Townlong Steppes holding open a portal between the Shado-Pan Garrison and Shan’ze Dao. Omnia Priests and Mages can also be found assisting adventurers seeking to gain reputation with the Shado-Pan. Frost and Fire mages have been witnessed among the ranks of the Omnia, along with Holy and/or Discipline priests. The discipline also contains scholars.
So… I guess we can say there might be Light-users among the Pandaren, but that they are treated more like scholars than as priests? Yalia Sagewhisper, as well as some Omnia Priest NPCs also directly refer to the Light in their ingame quotes, so it doesn’t seem like all Pandaren are ignorant of this particular force. (
Blizzard tells us that what is needed to acess Light and Void is mostly will-power, though we can argue about what the will has to be focussed on, and if the belief that one is doing good is required… In any case, if that is all, there is no reason to believe that Pandaren couldn’t have acessed it on their own, especially Shado-Pan monks, who spend quite a lot of time meditating and honing their spirit. Their version of Light casters would probably be different from the Church or the Draenei, since they don’t share a tradition, but that never bothered Blizzard before.