Though it never seems to address Aegis directly, leaving it open to interpretation...
Thanks.
I cannot find where (or even if) I wrote an Aegis HR. It is something that has never come up so I ignored it. Much as I do with many things that are immediate and obvious (it is the only way to stay sane and run a saga like this).
So I suppose it is open to discussion.
I think that to fret over penetration is a buzz kill and a time eater. It is the one spell everyone encounters, multiplied by many covenants to visit and/or interact with.
I say that knowing that the two PC's with that spell can penetrate at level. I mean, I am sure Thomas can get there with Mastery. Roberto also has Mastery, plus Life Boost. The covenant uses a Casting Tablet and I jsut handwave it. Botches are possible, yeah. So I hit Bellaquin with one 
Statistical Calculus gets in the way of handwaving and fiat. If the laws of averages are to apply, let them work out their balance and wrath on some covenant in Stonehenge :mrgreen:
If we are to adopt the burden of calculating Aegis Penetration, I advocate that we at least handwave boundary size. Not to say you could walk the perimiter of a city. No. But the castle or covenant building/grounds, big or small, is covered by the concept of Boundary as defined in that ritual.
Basically, I mean disregard Size Magnitudes for anything the size of a typical covenant or smaller, from vat areas like Ddurenmar and Doisitep to tiny enclaves like Varidian's Tomb or the Tower of Vulcanus. Same level = same protection.
And Aegis Penetration is really just a pain. Really.
We actually worked out what looks like a decent, workable house rule for the Aegis in my Stonehenge campaign. Basically, we more or less ignored the Boundary definition for Aegis, and HR'd that the boundary must be defined by the caster during the casting of the spell by walking the defining boundary, and that depending on the actual size of the Boundary, this may result in the spell taking longer (but not shorter) to cast than would be indicated by the spell level.
And as far as Penetration, we ruled that the Aegis must penetrate for the warding effect, but not for any of its other effects (e.g. to affect casting totals or magical abilities).
Just for comparison and contemplation.
Here we go again 
This is a mystery virtue. To being play with it, you should have the Cabal Legacy flaw.
May I suggest instead taking the "Imbued with the Spirit of Vim" virtue, like we discussed*? Or Leadworker maybe?
Much better on the skills, although I still don't understand why Finesse 4 given your spells. But it's your choice, no problem otherwise.
- In short, for those who are curious: Mercurian Magic + Imbued with the spirit of vim = cheap, or even free, Watching Wards
Nice!
Now that I think of it, since you wanted suggestions of rituals, a year variant of this is a possibility.
I was thinking if there would be a way for you to ritual cast a kind of Hermes Portal, but I don't see a way.
Yes, this is the same formula, I just use the one below, which is clearer IMO.
The difference between our math comes from the fact that you count a cult lore of 2, whereas I don't find any (despite having looked more than 5 times :-/ ). Maybe this was from a previous version of the character?
May I second all this very much?
IMO, it allows for some fun with the Aegis, from choosing an optimum aegis for keeping out creatures (Pen = lvl), to casting one specialised versus magical powers (Pen = 0), without the hurdle of your covenant being limited in size.
For that matter, I don't even see Mercurian Magic anymore. Did you make a fairly large change to the concept?
You know what it is? I probably screwed up the copy and pasting. I've been on the road since Friday, I'll have a chance to check tonight.
I know for a fact that I forgot to put Mercurian on it. I'll update the sheet tonight.