have a look at all the free shrug patterns at http://www.knittingpatterncentral.co...ory/shrugs.php
they have several loose fitting lace shrugs that would work very well at a wedding. i like the Miss Dashwood & I Do, but they are both snug to the body...something a bit more flowing may flatter you more.
also, be wary of yarns with fuzz -- the kidsilk could leave a bit of a mess on your black satin dress
look for a laceweight merino (morehousefarm.com), or a nice smooth silk. the alchemy silk purse yarn is yummy! (purlsoho.com)