If you are anything like me, you will have been surprised to learn that wall candle holders are known primerily as wall sconces. What is the history of this term? Wikipedia came to my rescue, as usual.

"A sconce is a type of light fixture affixed to a wall in such a way that it uses only the wall for support and the light is usually directed upwards. It does not have a base on the ground. The applies to traditional forms of torch lighting but aslo to modern gas and electric light sources affixed in the same way"

So there you go, another mystery solved. But why ( in my experience at least the term seems to have remained so alive in the world of candleholders rather than electric lighting, is still unresolved. Perhaps the traditional word just suits traditional lighting methods.