Those who have done it say it’s surprisingly easy. Legend has it that the practice of sabrage — opening a bottle of champagne with a saber — was started by Napoleon’s officers (who else?). This video demonstrates how it’s done.
The key to performing the deed correctly involves a very cold bottle — 40 degrees F, at most — and the confidence to deliver a swift and precise blow at the lip of the bottle. The rest is all swagger and spectacle.