“Sabrage /səˈbrɑːʒ/ is a technique for opening a champagne bottle with a saber, used for ceremonial occasions. The wielder slides the saber along the body of the bottle to break the top of the neck away, leaving the neck of the bottle open and ready to pour. The force of the blunt side of the blade hitting the lip breaks the glass to separate the collar from the neck of the bottle. One does not use the sharp side of the blade. The cork and collar remain together after separating from the neck.” Wikipedia
The origins of Sabrage are said to have come from Napoleon’s troops who received gifts of Champagne from people as they rode from their victory ground. They could not open the bottle with one hand on the reign and used their sabres to dislodge the bottle tops.