A wand is a straight stick that is used in Wiccan rites. The wand is used to draw the pentacle that closes the doors of the circle. A finger can be used, however a wand adds power to the rite.
A wand can be made of any wood, however ash has particular properties that make it a particularly good wood to use in ritual. Ash bleeds and the bleeding lance of Parizival resonates when using an ash wand. Wolfram is from Eschenbach and Esche is the German for ash. We cannot know whether the author of the grail was actually from Eschenbach or if it was a code but the assumption is that he was not. In the legend of Parzival the hero passes a man sharpening an stick of ash. This is a further referncence to a magic wand. The word ash means spear.
A simple stick of ash or any wood is often the best choice for a wand.