What do you wear to a medieval themed wedding?!

some of our friends are getting married in August this year and they're having a very cool medieval/lord of the rings themed wedding.
they will be Arwen and Aaragon and the person marrying them will be Gandalf, all at the beautiful Caerphilly castle! follwed by a hog roast!

I love the idea of themed weddings- I'm excited to see how this will work! ee! but the tricky bit now will be finding something to wear....

So far I really love this;


but I'm a bit worried it's too unconventional. but the, the wedding is in summer, so maybe I'll be grateful for a shorter dress and short sleeves.

I also found something a bit more traditional:


Ideas greatly appreciated...
I have to remember I'll have short hair by then though- I won't be very lord of the rings looking!