Changing Moons are a combination of three Castes in one. They are shapeshifters and sneaks, but they can fulfill other roles too.
Unlike the Physical or Mental Attributes, the Social Attributes often represent alternate methods toward a similar goal - you can lead a crowd through force of personality, you can ruthlessly twist them around your finger, or you can entrance them with your good looks.
While favoring Appearance may seem less valuable than, say, Dexterity, it can be put to many purposes. See BillGarrett/AppearanceHowto for suggestions.
The Anima ability for Changing Moons is not at all specific, and it is often overlooked (as TheMyriadOfShades points out) that the illusion it creates can be used in any form whatsoever.
What about (say) a Changing Moon adopting River Dragon (42') form, then using their anima ability to appear human? My gut instinct is to say "this is fine, and the illusion will break at whatever moment the Storyteller would be otherwise imposed upon to figure out the disparity between physical mass and assumed shape".
Charms From Favored Attributes
Changing Moons learn every last Charm in Lunar Shapeshifting at the discounted rate, and can learn a good smattering of Unarmed or Armed Combat. Out of combat, the Interaction and Knowledge tree is theirs. (needs expansion)
Leader of Soldiers
Emotion-Shaping Technique [prereq: Tale-Spinning Mastery] allows you to modify the Virtues (up to 2 points per Virtue) of any valid target, who need not even be listening to you. This works, for example, on the enemy commander's Temperance and Valor. Since Mail and Steel calculates Valor as the lower of the commander's or the unit's overall Valor, the Lunar can severely hamper an enemy unit whose commander is about as brave as his troops. And if he can't hear you from across the battlefield as you are charging at him, yelling insults, that's what Lion's Roar Method [prereq: Tale-Spinning Mastery] is for.
Courage-Building Address [prereqs: Crowd-Calming Pronouncement, Crowd-Inciting Method, Emotion-Shaping Technique, Tale-Spinning Mastery] lasts for "one battle", and with a decent roll (boosted by specialties or what-have-you), the Lunar can turn ANYONE into a Valor 5 war-machine. Mail and Steel gives this the following mechanical effects:
- "Entering combat with an obviously supernatural being" calls for Valor at +1 difficulty, or the unit hesitates. "Entering combat" is difficulty +0. A Lunar in war-form leading a horde of barbarians (or anyone else for that matter) will have his unit roll Valor (and at 5 dice, succeed virtually every time barring other factors), while his opponents will roll THEIR Valor (possibly reduced as above ) at increased difficulty. If they fail, they hesitate and lose their action. This doesn't even consider whether units are receiving missile fire at the time.
- Valor 3+ allows units to better resist Fatigue.
Glorious Battle Presence [prereqs: Courage-Building Address ...] gets even better. For five turns (that's long turns, per Mail & Steel rules, which can often be an entire engagement), your troops cannot fail Valor checks, you get bonus dice equal to Charisma in nearly any Mail and Steel roll, and the enemy is more prone to hesitation and rout ("intimidation or demoralization").
If several Lunars are bonded via Brotherhood of Lake and River, and they are all within range of each other and all leading troops, they can trivially adjust their tactics on the battlefield to help each other out, or respond to threats. And is there a wolf-sibling or Familiar flying over the battlefield, spying out enemy units?