Oooooh damn. Lovely update, all sorts of good stuff in there, but for now: LOOT
[] The ethereal green lights of the Grinning Moon.
{Laughing Flight of the Wind Thief; Mobility and Stealth Art}
[] The pale grey lights of the Hidden Moon
{Imperturbable Starlight Mantle; Defensive Social and Defensive Combat art}
[] The sparkling many colored lights of the Dreaming Moon
{Trickster King's Devious Oratory; Offensive Social and Spiritual Buff/debuff Art]
So, obviously the real answer is to take all of them and never ever let go. That being said, since we have to choose, I do feel the Dreaming Moon choice is slightly redundant with our current suite. That doesn't make it bad, but I think the other two choices might add more to the overall build.
Between those two, though... the Grinning Moon art seems like a flying/stealth art, which seems
great for our purposes, more stealth is definitely useful, and so is flying... a combination of the two, even more.
On the other hand, we are in dire need of a new defensive art, and TRF was something of an outlier to begin with, a successor seems unlikely - the Hidden Moon's art is a perfect fit for that, and I'd give better odds for finding an SCS successor than a TRF one, so perhaps this would be the time to take a defensive moon art.
Ultimately, I am leaning towards the mantle right now, but I have to admit that like 20% of that choice is purely because the description sounds awesome. If anyone has compelling arguments for taking Laughing Flight of the Wind Thief over Imperturbable Starlight Mantle, I may be swayed.