Just to be perfectly clear, at point 2 I did not mean enhancing Ceremony with Sympathy. I meant that if ... Sympathy-Enhanced ... Order of Hermes Lore, say, becomes a faerie supernatural ability, several users of it should be able to combine their efforts through Ceremony, gaining humongous Order of Hermes Lore totals. But I can easily see how one can just say no to this
Yeah, I'd probably argue that Order of Hermes Lore is not a Supernatural Ability, even though it is treated as a faerie effect after being enhanced, so Ceremony doesn't apply.
I think I'll just take the stricter ruling! Sure, allowing Dark magic to "realign" to magic sympathy-enhanced abilities is no big deal for a shoemaker. But it definitely is for a maga at Tribunal using e.g. her social skills, enhanced by a Sympathy in ... say Debate, to sway her sodales. A sympathy trait of +3 would then grant an effective bonus of +10, which seems a lot.
Sympathy Traits can be used as specializations to boost Abilities used to perform Hermetic magic, including Penetration and Magic Theory. When affecting Abilities that govern lab activities, such as when boosting Magic Theory, the magus must experiment to receive this benefit, and he automatically experiments if he possesses a negative Sympathy Trait that is applicable to his laboratory project.
There are more specifics, but that's the part that covers if they apply.
I am fairly sure that at tribunal a pair of magi will have second sight and a pairnmore sense holiness and unholiness. A maga using dark sympathetic magic will get a touch of attention from them. If not a case of breaking the Code for having dealt with demons to acquire those abilities. Careful with your ability usage
Dark/chthonic magic is not necessarily diabolic or even evil, and so it's quite ok for the Order (RoP:I, p.123), even though individual magi might dislike it. Then again, to perceive its taint in a fellow magus, you need to use magic to peer into his affairs. And this brings us to the second point.
Using second sight and/or sense (un)holiness on your sodales violates the Hermetic Oath. Technicallly, you can be (should be, in fact) marched for it.
It's worse than that, because you might not survive to be Marched: If there is something to be seen, you have to roll to see it, you don't get to choose. Think of all those stress dice, all those botches, all those Warping Points. And maybe even if there isn't something to be seen, because SS can tell you there is nothing to be seen.
But you can keep them shut, stay blindfolded, or keep your gaze averted, or use your own magic to suppress your awareness of what you see.
Now, is anyone going to force you to do that? Unlikely, if you keep your mouth shut. But if you start saying around "I saw this aura on magus x", "I saw this spirit whispering in the ear of magus y", it starts to be much more likely.
Second Sight doesn't need to penetrate. Sense Holiness and Unholiness does. That creates a significant difference with one thing never pinging off Parma Magica and the other repeatedly doing so.
There are more specifics, but that's the part that covers if they apply.
Hmm, well that does make it clear that they can be used during casting, doesn't it? Sorry! I guess the compromise I'd suggest there is that doing so still makes the Hermetic spell more dangerous. You have to use a stress die, and you should get additional botch dice as if you were using a faerie power in non-faerie auras.
I remember being really concerned that characters shouldn't be using Sympathy Traits with magic from the other realms, but there's always a desire to include mechanics that magi can use, because everyone plays magi. So the section under Hermetic Charms is slightly different from the bits that come before, like how negative Traits work in the lab.
Highlight it. Click on the upper-left where it says "quote."
That's actually pretty consistent unless there is something I'm forgetting. If you have an applicable negative Trait, you must use it, and then all the botch stuff shows up, too. You get to choose if you use positive Traits, but not negative ones.