Naya had no such easy out for dealing with her outfit, not being a member of organized faith of any kind (even though she did pay tribute service to The Great Dreamer).
The outfit she was wearing for the last week was out of the question anyway, being pretty much opposite of "fancy", and the geneerosity of Lady Verala, while couldn't be overstated, didn't help much here. Granted, with the Mayor's generous reward, she could easily afford almost any dress she would want... but spending money on clothes seemed so pointless. Lamenting the impossibility of adopting the customs of her new philosophy, the sylph considered her options again. Chelaxian formal dresses were out of the question; she couldn't imagine how people managed to breath in them. On the other hand... formal - perhaps even noble - dresses of her homeland... she spent long decades dreaming of owning something similar one day, and to this day never did. (At first, she didn't have hearly enough money; and Naya didn't get reach until after meeting Kaylee... at which point it became moot)
But, if one think of it, at the formal meeting, a formal dress was a necessity, just like armor was on a battlefield. The question was in finding a clothier able to sew one quickly enough, but Naya could compromise on quality, as long as it didn't affect the look. She wasn't expecting to wear the dress often after tonight, after all.
In the end, she ended up wearing a relatively simple white dress with blue trim, simplicity and strictness of the design themselves indicating higher class - Naya's enchanted necklace, bracelets, tiara and belt serving nicely as accessories one was supposed to wear with it. As an added bonus, the dress was light, sewn from a thin cloth, and allowed the wind to reach her skin somewhat at least. (Naya toyed with the idea of copying Lady Hathor's favorite dress as depicted in the scrolls found in Akhentepi's tomb, but decided not to press her luck after all)
As for the feast itself... what kind of adventurer ever refused a good meal? The fact that she was no threat to Major's vine cellars just meant she had to redouble the efforts on food.