Definition: bladed corkscrew

Also known as a double-bladed corkscrew or corkscrew, with its protective case. These models were widely used in the 19th century, allowing corks to be extracted without damaging them. French model by SANBRI, patented by Albert Tabard in 1951. The handle and case are made of aluminium. The blade is secured with a screw, making it easy to attach and remove a replacement blade, which is missing on the model shown.

Using a blade corkscrew is not that easy, but it is essential when dealing with a cork that has become brittle. If the first attempt with a spiral corkscrew has failed, using a blade corkscrew can save you because it grips the cork in a more delicate way from the outside.
First, the corkscrew uses the edge of one of the blades to cut the foil above the bottle's ring in one swift movement. The cork is then removed, compressed between the two blades. The air that enters with the blades slowly mixes with the wine, thus avoiding the sudden shock of air and wine, accompanied by the characteristic "flop" of the vacuum seal. The creation of a vacuum requires increased traction on the spiral corkscrew, which can be fatal on a weakened cork.
Longer corks, which often pose a problem, are removed from the neck of the bottle with equal ease using a double blade.
Insert one of the blades, the longer one, between the cork and the neck of the bottle, then insert the second blade and advance both blades successively with a left-right movement, applying slight pressure until they reach the stop. Then extract the cork, using a rotating movement at the same time as pulling.

For vintage ports, which are often very old and whose high alcohol content has weakened the cork, and other very old vintages, this method should be used immediately.
Note that it is suitable for both right-handed and left-handed people. Wine lovers always have this second backup model at their disposal.