The Mark
Adapted by Maurice Lane, based on material provided by Prodigal, Neel, Beth and Maurice Lane
When Lucifer had the angels loyal to God's original plan in custody, he found himself with a problem: the rest of Heaven might be tacitly acquiescing to a coup, but they wouldn't tolerate a massacre. Frankly, the Archangel of Light wasn't even certain that he and his weary supporters could prevail against a group of celestials with nothing left to lose. Exile was thus the only real option left.
However, when the Lightbringer cast out the Loyalists from Heaven, he added one last note to their punishment. Why is a matter of some debate: some angels say it was prudence, some say it was pettiness. A few, deep in their cups (substance abuse has been rising among celestials in the last few centuries: why do you think they call distilled alcohol 'spirits'?) suggest it was both. The only one certain is Lucifer, and he's not talking.
Physical Description
The Mark is simply a letter in Angelic permanently inscribed on the very being of a celestial. In corporeal form, this usually resembles some kind of odd tattoo, somewhere on the body: despite human legend, it doesn't have to be on the forehead of an angel's vessel. Angels in the ethereal plane will usually have the Mark manifest as a symbol of shame or degradation: a prisoner's uniform, a brand on one cheek, or anything else that fits the current environment. The celestial form of the Mark is a large, fiery letter that shines from the forehead of the afflicted angel.
Game effects
First off, the Mark was designed to prevent the Exiles from sneaking back into Heaven, and it does this quite nicely. While on the Celestial plane, a Marked angel will be instantly recognizable as such. Even on the Corporeal plane, those with the Mark and in celestial form will be recognized if the onlooker makes a Perception roll. Of course, those without the Mark can sneak into Heaven, but any Unmarked Exile caught in Heaven is in for an interesting demise.
Second, those with the Mark may not retain, and may not be given, any Attunement, Distinction, Rite or Word by an Archangel that does not have the Mark.
Third - and this was not intended by Lucifer - Hatiphas designed Sorcery firmly with the Mark in mind. Marked angels may not be randomly Summoned, and get a bonus to all Will-Wars equal to twice their Celestial Forces.
Wearers of the Mark
Any angel formally exiled from Heaven will bear the Mark, as well as all their descendants. If an angel with the Mark creates a new celestial with one that does not, the new celestial will also bear the Mark. Officially, the only way to have the Mark removed is to submit to the will of Heaven and return to the fold of the Host. The procedure is painful, and has the side effect of burning away all the Attunements, Distinctions and Rites that have been granted by an Exiled Superior. Being aligned to most Exiled Words also brings with it the Mark.
However, not all Exiles bear the Mark. At least two Major Superiors (Ogiel and Lilith) were elsewhere when the Mark was given out, and thus did not bear it - even when promoted to Archangel. It's thought that the two were already Superiors through some ineffable means, and that the ritual merely confirmed their status. Whatever the reason, Servitors of Resistance and Freedom do not bear the Mark unless they also accept an Attunement or Distinction from an Archangel so Marked. Note that no Word-bound of these two Archangels bears the Mark, either.
Also, no Lilim will ever bear the Mark, under any circumstances: attempting to impose it will fail. This is one reason why there are not as many Lilim in Heaven as there could be - how can you trust one to not be a spy?
Finally, occasionally an angel from the Host will be able to flee from Heaven with his or her Heart and make it to the Exiles. Such angels are an interesting problem: if they are realigned to a Word whose owner does not hold the Mark, then they can keep both their old Attunements, Distinctions, Rites and Words and whatever rewards given to them by their new Superior. However, this may result in a Servitor assigned somewhere they might not be perfectly suited. Thus, the ultimate destination of any Servitor must be examined for its cost-effectiveness. Still, there are many Servitors of Resistance and Freedom In Service To other Superiors.
There is a minor, but real, undercurrent of tension between Exiles that bear the Mark and those that do not. Those that do not are, after all, mostly descended from angels that were never humiliated by Lucifer: they take a certain amount of pride in that fact. After all, they were never captured. They never just gave up and tamely submitted to imprisonment. They kept the War going on … and, eventually, they were, in fact, the ones that eventually busted out the rest of the Exiles from Hades. They have nothing to prove (with the subtext that everybody else does).
Needless to say, the rest of the Exiles don't quite see it that way. Those with the Mark bear it as a badge of pride, rather than shame: from their point of view, it's a constant statement that Heaven found them too dangerous to either kill or keep around. Those that do not bear it are either angels that ran away, or later defected: can they really be trusted to stay the course? If Hades is invaded, will the Unmarked stand their ground, or will they run away again? Besides, Hatiphas' little maneuver, turning the Mark into a decent protection against Sorcery, is a source of some amusement to the Exiles: this immunity to Sorcery is now practically the definition of a proper Exile. Unfortunately, those without the Mark can't quite join in the laughter at Lucifer's expense.