Wotcha Maid Marion! Hahaha! I really like that actually. The sleeves look like they've been tacked on as a bit of an afterthought but I think that is fault of the photographer rather then the dress. Do it!
Rather than prancing, beer wielding medieval wenches, every time I see an excessive shoulder I think of American footballers. But you're staying on the right side of epic proportion babes. Just enough shoulder volume to prove useful at rush hour and no more. If you do go bigger be warned, it will be a licence for me to be able to start wearing things like this:
and you know I'm just waiting for an excuse, so proceed with caution.