>Froslass is most likely based on Yuki-onna, a female ice-spirit of Japanese folklore.
This is the picture of Yuki-onna from Wikipedia (I know it's an unreliable source, but it's the picture I could find.)
It's kind of hard to see the similarities, but this is what I've found:
-Both of them are female.
-Both of them have some sort of band or belt tied around their waist.
-Both of them have to do with ice/snow.
-Both of them have a longer end of their dress sleeve hanging down at the end of their sleeve. (I hope I explained that well.)
>It also reminds me of snow angels.
Yes, they do look kind of like angels!
Hope this helps!