What was the significance of the black bra?

It just means that she is in mourning and this is a very black part of her life. Hope that helps.

I just thought it was a fashion statement. It used to be a faux pas but you see it all the time now.

When you get up in the morning, how do you decide what shade of black to wear? (Shallow Grave)

She likes to wear black bras. Other than that, it doesn't mean a damned thing.