Imlike that design. however, the cat is not a familiar. he might become one, but IMO we can reserve thar decision for later, when he really decides to bond with Fleur. Right now he is just enjoying the antics of the young maga.
Okay, made some tweaks- the biggest is that I noted in ROP:M that magical animals can buy their pre-size adjusted stats normally, and given that the mental stats were net-negative used this to boost her com score from -4 to 1
I got the impression that the ritual power to allow second sight had met approval so I left it in (which allows the cat to 'lend it's eyes' to other characters)
Characteristics
Int 0
Pre -2
Str -7
Dex 3
Per 1
Com 1
Sta 0
Quick 4
Flaws
magical freind(minor-1)
nocturnal(minor-1)
craving for travel(minor-1)
greedy(major-3)
delusion(minor-1)
Virtues
perfect balance(minor+1)
Puissant Awareness(minor+1)
sharp ears(minor+1)
unaffected by the gift(minor+1)
voice of the city(minor+1)
second sight(minor+1)
arcane lore(minor+1)
Qualities
gift of speech (minor +1)
Personal power :hands of the magical animal (minor +1)
Vis mastery (major +3)
Ritual power:grant minor virtue(second sight) (major +3)
improved confidence x2 (minor +2)
Abilities
cat speak 5
athletics 3
awareness 4
brawl 3
stealth 4
hunt 4
Occitan 5
Latin 5
Second Sight 5
Basque 4
Classic Greek 4
Portugeuse 5
Leonese 4
artes liberales 2
Guile 4
Magic Theory 5
Magic Lore 4
Faerie Lore 4
Finesse 5
Teaching 7
Order of Hermes Lore 7
Might I suggest Gift of Tongues, so you don't have to take so many languages. The cat has no ArtesLierales and cannot read. You should sprinkle in a few Inferiorities for flavor. Make sure the cat has the power to open doors or walk through walls. A set of hands maybe? Garfield style naturally 
.
It does not matter what the cat's past actually was. It claims it has been a familiar for generations. But maybe it doesn't know what that really means? Or maybe it doesn't really matter since there is no way to proove or disproove it. Maybe the cat is a manifestation of a magical concept that reemerges into the material world from time to time.
Whatever it is, it is all just fluff. 
It has hands of the magical animal, so that should suffice to open doors (actually I have seen perfectly mundane cats open doors...
In terms of its past, it makes lots of claims, some of which cannot simultaneously be true (for example he claims to have been a familiar to both Bonisagus and Jerbiton), but since cats are not exactly know for forthrightness most people take these to be just stories. What is clear is that he at least knew both of the founders.
characteristics
Int 1
Pre -2
Str -7
Dex 3
Per 1
Com 3
Sta 0
Quick 4
Qualities
gift of speech (minor +1)
Personal power :hands of the magical animal (minor +1)
Vis mastery (major +3)
Ritual power:grant minor virtue(second sight) (major +3)
improved confidence x2 (minor +2)
susceptible to deprivation (minor -1)
reduced attack (claws) (minor -1)
reduced damage (claws) (minor -1)
improved characteristics x2 (minor +2)
personal power: human shape (minor +1)
Virtues
perfect balance(minor+1)
Puissant Awareness(minor+1)
sharp ears(minor+1)
unaffected by the gift(minor+1)
voice of the city(minor+1)
second sight(minor+1)
arcane lore(minor+1)
Flaws
magical freind(minor-1)
nocturnal(minor-1)
craving for travel(minor-1)
greedy(major-3)
delusion(minor-1)
Abilities
cat speak 5
athletics 3
awareness 4
brawl 3
stealth 4
hunt 4
Occitan 5
Latin 5
Second Sight 5
Basque 4
Classic Greek 4
Portugeuse 5
Leonese 4
leadership 2
Guile 4
Magic Theory 5
Magic Lore 4
Faerie Lore 4
Finesse 5
Teaching 7
Order of Hermes Lore 7
I like your outlook on the cat's mentality 
Cats can open some doors, but it is difficult, and these are old heavy medieval doors. And having No Hands is a Flaw for a good reason . Hands of a magic animal means it has a magic quality or power that give it hands. I suggest...
The sum cost is a Minor Quality for a Personal Power.
You don't need all those languages. Take Reduced Abilities four times, then take Arcane Lore and Educated. Net Value equals the same number of xp, and you have space for two points of Qualities. Gift of Tongues and Personal Power.
Zip-zam-zoom, all covered.
Remember, you must take Arcane Lore and Educated in order to be able to spend any xp on Arcane & Educated Abilities.
Only thing is I can't find gift of tongues under magic, I can find it under faerie powers, but not magic...
I'll trade the human shape for The Proper Beast from my last version
Gift of Tongues is a Minor Heroic Virtue from True Lineages. I know, Ars Magica has become goofy like that. RoP-Magic mentions several times that Magic Characters can take Heroic Virtues.
I find the cartoon anthropomorphic feline style more aesthetically appealing, but the choice is yours. What? You want to look like a hooman?
Just razzing. Go for the style that fits your style best.
Characteristics:
Int 0
Pre -2
Str -7
Dex 3
Per 1
Com -4
Sta 0
Quick 4
Flaws
magical freind(minor-1)
nocturnal(minor-1)
craving for travel(minor-1)
greedy(major-3)
Virtues
perfect balance(minor+1)
Puissant Awareness(minor+1)
sharp ears(minor+1)
unaffected by the gift(minor+1)
voice of the city(minor+1)
second sight(minor+1)
Magical Qualities
gift of speech (minor +1)
Personal power :hands of the magical animal (minor +1)
Vis mastery (major +3)
Ritual power:grant minor virtue(second sight) (major +3)
improved confidence x2 (minor +2)
Personal power (The Proper beast) (minor +1)
reduced abilitiesx2 (minor -2)
Gift of Tongues (minor +1)
educated (minor +1)
Abilities
cat speak 5
athletics 3
awareness 4
brawl 3
stealth 4
hunt 4
artes Liberales 5
Latin 5
Second Sight 5
leadership 4
guile 4
magic theory 5
magic lore 4
Faerie Lore 4
Finesse 5
Teaching 7
Order of Hermes Lore 7
Classic Greek 5
Philosophae 4
hedge witch magic theory 2
I can't see its might. What it is? Likewise, you should list its size and confidence.
I suggest you give it some personnality traits, most notably Cat+3
It should have at least some of the (free) Animal Qualities from the Book of Mundane Beasts, that is: Ambush Predator, Crafty, Good Jumper, Skilled Climber, and Thick Fur.
Do you really need Vis Mastery? I understand you took it to fuel its Ritual Power, but remember: He only loses the Might is granting the virtue forever. As it is, he could give a grog Second Sight for a day, withdraw it, and then regain its might. Unless, of course, you want him to grant the virtue forever (like, to all our grogs), in which case it is a good choice.
Dispensing with Vis Mastery could otherwise allow you to lesser up to half of the Ritual Power cost (by taking Improved Powers), and take one less Reduced Abilities, taking some Area Lores, for exemple.
Assuming its base might is 10 (which should give a final might of 13), it has one Magical Quality in excess.
However:
- Voice of the Town and Gift of Tongues are redundant. You should take only one, which solves the problem
- Hands of the Magical Animal and The Proper Beast are different, but you could easily dispense with one, depending on your concept and wishes. This would allow you to take Arcane Lore, which is needed for it to have Magic Lore, Faerie Lore, and Magic Theory.
I have not computed XP, I trust you on this. I love its OoH score
Yes, you do need Arcane Lore. -1 Reduced Abilities equals -25xp, +1 Arcane Lore equals +50xp. It's a net benefit.
I did not realize Hands of the Magical Beast was a power. My bad 
I thought that was a figure of speech scoffing at doors. I feel stupid
I suggest that instead of Proper Beast, be unique.
I forgot the inferiority:
susceptible to deprivation (minor -1)
also a second benefit of vis mastery is that they can convert confidence points to vis...
Looks like there were other aspects I didn't post, let me repost this...
Characteristics:
Int 1
Pre -2
Str -7
Dex 3
Per 1
Com 3
Sta 0
Quick 4
Qualities:
gift of speech (minor 1)
Personal power :hands of the magical animal (minor1)
Vis mastery (major 3)
Ritual power:grant minor virtue(second sight) (major 3)
improved confidence (minor 2)
susceptible to deprivation (minor -1)
reduced attack (claws) (minor -1)
reduced damage (claws) (minor -1)
improved characteristics (minor 2)
Personal power :The proper beast (minor 1)
reduced abilities (minor -2)
Gift of Tongues (minor 1)
educated (minor 1)
Virtues
perfect balance(minor+1)
Puissant Awareness(minor+1)
sharp ears(minor+1)
unaffected by the gift(minor+1)
voice of the city(minor+1)
second sight(minor+1)
arcane lore(minor+1)
Flaws
magical freind(minor-1)
nocturnal(minor-1)
craving for travel(minor-1)
greedy(major-3)
delusion(minor-1)
abilities
cat speak 5
athletics 3
awareness 4
brawl 3
stealth 4
hunt 4
artes Liberales 5
Latin 5
Second Sight 5
leadership 4
guile 4
magic theory 5
magic lore 4
Faerie Lore 4
Finesse 5
Teaching 7
Order of Hermes Lore 7
Classic Greek 5
Philosophae 4
hedge witch magic theory 2
intrigue 4
For her sanctum, assuming that 'no staff' can represent not the expenses being consumed but not yet being allocated (since fleur did arrive rather suddenly):
strong aura 3
haunted -1
uncontrolled regio -1
superior engineering 1
hidden resource x3 3
no staff -3
secluded 1
Base Might 10, I guess?
Size?
If you want to keep proper beast + hands of the magical animal, ok.
If you took Vis Mastery for her to be able to create Vis, you might be better of with taking a Personnal Vis source. It depends on a lot of factors
IMO, just for the vis, Personnal vis Source 3 is better. There are other possibilities, though. Like, you could take Improved powers once (reduce the ritual power cost as much as you can, up to half), take Personnal Vis Source2. Or take it once, plus another personnal power, like a Leap of the Frog that enables him to do great jumps. It all depends on what you want to do, what happens... I can't really give you a good choice, just bounce ideas around
I see he has Finesse 5. If you intend to equip him with magical items or effects (or if he has a Leaping power), it is a fine choice. Otherwise, it'll only be useful if you want him to teach it. Which can be great, a covenant can always use grogs trained in Finesse.
Otherwise, I'd say just pump these into MT, you deserve it, and him too.
I expect she will teach finesse, though I do want to consider the alterations you have suggested which may make it even more useful (with teaching 7 and com 3 that is a base SQ of 13, or 19 teaching 1 on 1, I may trade one of those levels for good teacher...)
I would like to point out that Ritual Powers already allow you to spend Confidence (RoP-Magic, p. 40, middle column, last paragraph).
You don't need The Proper Beast on top of Hands of the Magical Animal. I did not realize Hands was an actual power, until I saw your write up of it (and am now reading in on page 30 of RoP-Magic). Proper Beast is my aesthetic preference because I invented it and named it after an old 4th edition spell, and I like the idea of cartoon cat shapes . Hands is cheaperthough.
Vis Mastery allows you to consume vis as Confidence though, a valuable asset. Something I bet Roberto wishes he could do
Then there is Fatigue Mastery. Spend Fatigue as Might, Might as Vis, then Vis as Confidence :mrgreen:
Felicia:
cat (size -3) Might 10+3(for size)
Characteristics:
Int 1
Pre -2
Str -7
Dex 3
Per 1
Com 3
Sta 0
Quick 4
Qualities
gift of speech (minor 1)
Personal power :hands of the magical animal (minor1)
vis sourcex2:creo (minor 2)
Ritual power:grant minor virtue(second sight) (major3)
improved confidence (minor 2)
susceptible to deprivation (minor -1)
reduced attack (claws) (minor -1)
reduced damage (claws) (minor -1)
improved characteristics (minor 2)
Personal power :gift og the frog's legs (minor 1)
reduced abilities (minor -2)
Gift of Tongues (minor 1)
educated (minor 1)
improved powers (minor 1)
Virtues
perfect balance(minor+1)
Puissant Awareness(minor+1)
sharp ears(minor+1)
unaffected by the gift(minor+1)
good teacher(minor+1)
second sight(minor+1)
arcane lore(minor+1)
Flaws
magical freind(minor-1)
nocturnal(minor-1)
craving for travel(minor-1)
greedy(major-3)
delusion(minor-1)
Abilities
cat speak 5
athletics 3
awareness 4
brawl 3
stealth 4
hunt 4
artes Liberales 5
Latin 5
Second Sight 5
leadership 4
guile 4
magic theory 5
magic lore 4
Faerie Lore 4
Finesse 5
Teaching 7
Order of Hermes Lore 7
Classic Greek 5
Philosophae 4
hedge witch magic theory 2
intrigue 4
At first glance, it looks ok to me. You only need to stat out the powers, I can do it for you if you want.
You should give him some personnalities traits, too
So, we have a cat that can (I guess) stand upright, jump great heights and stand on narrow beams, manipulate items à la chat botté, speak in about all tongues, perceive hidden things and grant for a time this power to others, yet is very knowledgeable about the OoH and a valued teacher. Having lived for so long and survived many perils, he is very confident in his abilities, and has discovered a few vis sources he keeps on hand. Does this looks fine to you?