From the RoP:M pg 39, there is an ability to Grant a Minor Flaw to a target, either temporarily (as long as the Magic Point is not recovered) or permanently (with a ritual). Once this Flaw is in place on a target, what are the rules for a Hermetic spell to remove the temp or permanent flaw?
The PeVi guidelines reference the level of the effect to dispell, but how do you determine that from the Might Point cost of a Power?
I think that minor virtues and flaws count as level 25 ritual spells and major ones count as level 50 rituals*. Some sagas rule that rituals are harder to dispel than non-ritual spells; others rule that it is just as easy. (RAW doesn't distinguish between them (so just as easy) I think.)
*My RoP:M book is being lent to a friend, but metacreator lists those powers as being those levels. Since might costs can be changed with extra levels, you can't just use those costs to decide the level.
Grant (Minor Virtue) takes a Ritual Power magic quality, which would put it at level 25; Grant (Major Virtue) takes two, for level 50.
This is also the equivalence for Minor and Major Flaws given through the Bind Curse Inner Mystery of House Verditius, so it should be pretty solid.
Oh, and in the case of those curses, the guidelines to remove them specify that if the person has the Gift, it is a good idea to increase the target to Part to make sure not to damage it in the process. Although I suppose you could tailor a PeVi spell to a specific Grant Virtue effect. Which you'll probably have to do anyway because Unravel the Fabric of (Form) won't cover those non-Hermetic effects, and it would take a very high level Wind of Mundane Silence to remove them...
Or, you know, you could just put an arrow through the heart of that pesky magical squirrel who thinks he may grant free virtues to your enemies Or cast your favorite version of Dragon's Eternal Oblivion at it...
For the temp version, others have answered (and correctly) above.
As for the permanent version, decreasing the Granter's Might score permanently? Too bad - can't be dispelled any more than any other Flaw.