In the description of the Perdo Vim spell Wind of Mundane Silence is written:
Is WoMS limited to just Spontaneous and Formulaic spells? Or can it dispell active powers cast from the enchantmetns in Talismans and Familiar Bonds? Presuming the protection from Parma Magica/Magic Resistance is overcome.
What of the power from Mythic Blood?
I don't understand why you bring MR into the picture here. MR would be relevant if you try to remove the effect from a target that is protected, I think, but any MR protecting the origin of the effect should be irrelevant. The effect is no longer part of the caster.
As written WoMS is limited to spells, but a similar spell for other kinds of effects would be possible. Personally, I think you could make a spell which covers both without any drawback.
When the restriction is there, I think it is just the sloppy wording of the 1980s editions that have never properly been reviewed.
In game, one could imagine this being a crude spell from the early days of the order, before the magi had fully grasped the generality of Bonisagus' theory.
Sorry for phrasing this as if I know; it is of course just my reading.
WoMS uses the Perdo Vim Guideline (bolding mine, and watch the errata!):
Dispel any magical effect with a casting total less than or equal half the (level + 4 magnitudes) of the Vim spell + a stress die (no botch).
So it makes sense, that also WoMS can dispel magical effects besides Hermetic spells.
I mentioned MR because I thought it might be applicable in a case like:there might be a familiar with Might, and the Familiar Bond is generating a shapechange spell on the Familiar.
OK. There we agree. I objected because I think MR would protect also spell effects active on the familiar.