Based on what Rarity dreams of at night, the look on her face is herself smirking at Princess Twilight that has enough expression on it to make Twi tell that Rarity is thinking, "Hey Twilight, I have finally got my wings as well as you! The only difference is I have had wins twice in my life & you've only had them once and BOTH of my wings are more fabulous than yours, you mad?" XD Idk, that just randomly came out of my mind as I was typing this!
This reminds me somewhat of your pic of Rarity cosplaying Remilia Scarlet (another of my faves). Speaking of which, I'm a writer, and I'm doing a Touhou/MLP: FIM crossover. Since the Gensokyo girls fly everywhere, I had Twilight Sparkle revise the wings spell to make them pegasus wings. So in that particular fanfic...well, this is pretty much what I imagined Rarity would look like. ^^
Also: a temple to Rarity...would be a simply fabulous idea!