Do you use wire? even then how does it stay up?
I think I might try and find out how to make and make a purse cake for my daughters 6th B-day.
I use acrylic tubing - similar to what they sell at aquarium/hardware stores
You just moisten your fondant and wrap around the tubing - secure to cake using a satay stick/skewer, one end inserted into the cake and the other up the end of the tubing.
This way you can do it and use it straight away and not chance of breaking - you get a nice curve as well.
Use the Rice Krispie treats to form the handle then use the fondant over it. You should be able to form it onto your cake and get the look you want. HOpe it helps,
I used a toothpick on each side, half of it was up in the handle and half was inside the cake. You can check my pics, or click on my Flickr link below, it's the very first photo.
I put toothpicks at each end, lay it on some parchment in the desired shape, and then let it dry before adding it to the cake.