this form is sponsored rather than researched; Johann did make some attempt to understand it, but eventually concluded that it was inherently magical and didn't really make much biological sense.  As such, he prefers not to use it unless he really needs to pretend he's a fae.  Still, it made a great platform for [i]learning[/i] how to fly, and opened the way to being able to use other aerial forms.  Note to the GM: I have no idea if a male sylph form can exist; if it can't, that's another reason for Johann to find the form intellectually annoying.

-1 wings
-1 claws
-4 supernatural speed
-2 inhuman toughness
-2 inhuman recovery
+3 catch (adds in cold iron & winter trappings in addition to all of Johann's normal vulnerabilities - though consequences from such can be healed by recovery powers in different forms)
-1 strafe attack stunt (+1 to fists attacks when flying)
-1 paranoid? probably. (+2 to alertness vs. ambushes)
-1 sex appeal (+2 on rapport to seduce an appropriate target)

+5: scholarship, athletics, alertness
+4: rapport, empathy, lore
+3: fists, presence, investigation, endurance
+2: stealth, deceit, discipline, survival
+1: performance, conviction, contacts, might, resources

Specific form details:
One form should match Lady Austris (and comes with the note that using it without Austris' explicit permission is a dangerous thing to do).
One form matches the human form he's dubbed Gretchen (Lenna Margerethe Weber).

Unless told otherwise, I'm assuming that trying to make a male sylph form just doesn't work.