You shan't recieve either. Ars Magica is purposefully vague in some areas as to be able to incorporate a variety of styles of play.
You know my view. Do what works for your saga. In my saga, I would allow a vis focus, ut it only applies to spells and enchantments that target vis.
on the side, the wands thing is cool, as it is only a specific subsection of enchanted items. There is precedence in RAW concerning familiars (a focus in familiars or the type of animal the familiar is contributes to all enchantments to the bond).