Trying to squeeze one more Flaw point out of a magical cat, I figured it would be cool to give her Restricted Power, requiring her to curl up in the lap of the target of one of her powers (giving comfort to someone--having the cat curled up in the lap seemed extremely appropriate). This was all well and good, until I realized I could make Restricted Power into the Minor Flaw Inferiority, and then, checking the power in question, I noticed that it was level 25--in other words, the power became utterly free, since the Minor Flaw Inferiority exactly cancels out the Lesser Power Quality. Indeed, if I pick powers with under 25 levels, I can obtain a "net profit" on the "transaction".
Obviously, something is wrong here, but I'm at a loss for what a reasonable limit would be.
The Minor Quality Lesser Power gives you 25 levels of Power, at a cost of 1 Quality point.
The Minor Inferiority Minor Flaw (Restricted Power) gives you a free Quality point.
The upshot is that is that you can get a 25-level Lesser Power (albeit a Restricted one) completely free.
Indeed, you can even a power (of less than 25 levels) for less than the cost of Restricted Power: in theory, if, for example, you buy 15-level Powers and take Restricted Power for each of them, you can get an infinite number of free levels that can be applied to other, higher-level Powers.
Does that make sense, or do you need detailed examples?
Yep but not.
You reduze a Power in 25 levels, and you get other down by the Inferiority. You can take the inferiority for example to "divide" a Greater Power, that make a 25 level effect without any more; and then with the inferiority take another 25 levels lesser.
It's like say that if you buy a bublegum of flavour Aby 5 centims and you sell it another of flavour B by 25 cents, you don't have two bublegums, you have one. The Inferiority works only if the power have more levels. You then are buying/making one power restricted, but still bieng compensate. One Flaw/Inferiority by Virtue/Quality, the base all day routine in Character Creation of Ars Magica 5th edition.