Balisongs And Caviar A Balisong Collector Special Exhibit C23 The double-edged spear-point blade is made of Devon Thomas Damascus steel. It features a pronounced fuller. A fuller is the grove down the median ridge of the blade. Fullers are sometimes called "blood grooves." There are two common misconceptions/myths that abound about fullers. The first is that this groove is they are to allow blood to come out of a stab wound. The second is that the groove is there to allow air to enter in as the blade is withdrawn from a stab wound so that the blade will not be held back by vacuum pressure. Neither of these fables is true. The purpose of a fuller is to make the blade stiffer and stronger. At first, it seems counter intuitive that taking material away can make the blade stronger. But it does. In building construction, I-beams are often used because they're actually stronger than solid bars would be. Here's an engine connecting rod. Notice how material has been removed from the beam of the rod much like a fuller on a blade. This actually makes the part lighter AND stronger at the same time. A blade fuller accomplishes the same two goals. Notice the very slight horns and adjustable pivot pins.