Square Enix shared screenshots of Terra Branford and Kefka Palazzo in their third form outfits. Both of these costumes were inspired by artwork from Yoshitaka Amano.
Terra (third form on top, old outfit on bottom for comparison.)
Kefka (third form on top, old outfit on bottom for comparison.)
As you may have heard… Vaan is in Dissidia 012[duodecim]: Final Fantasy. Here’s what he looks like preparing for a Quickening and fighting Gabranth dressed as Basch.