This is from PromGirl.com, which was the first thing that Google spat out when I searched for “prom dresses.” In no order, the four most egregious I saw (I did not look at every single one, but rather searched categories). It’s interesting, because I can see elements of Westerosi style in the majority of these dresses, but it’s by and large more spread out in this less designery setting.
This Cap Sleeved Long Prom Dress is your standard Margaery gown, for sure. This designer is riffing on this theme for sure, as are an alarming amount of other designers.
Here’s a Long Halter Bow Keyhole Dress to satisfy the halter requirement. It’s a much more severe color than canonical halters, but the keyhole got me.
Oh look a blue Cap Sleeve Open Back Lace Prom Dress for all your tamed-down Daenerys elements.
This here Floor Length Sleeveless Prom Dress with Embroidered Lace Bodice decently satisfies my “inspired by tit armor” requirement.
–your fangirl heroine.