the blade's stiffness. The edges of a cutting sword are almost parallel. Blades oriented for the thrust have thicker blades, sometimes with a distinct midrib for increased stiffness, with a strong taper and an acute point. The geometry of a cutting sword blade allows for acute edge angles. An edge with an acuter angle is more inclined to degrade quickly in combat situations than an edge with a more obtuse angle. Also, an acute edge angle is not the primary factor of a blade's sharpness. The part of the blade between the center of percussion (CoP) and the point is called the foible (weak) of the blade, and that between the center of balance (CoB) and the hilt is the forte (strong). The section in between the CoP and the CoB is the middle. The ricasso or shoulder identifies a short section of blade immediately below the guard that is left completely unsharpened. Many swords have no ricasso. On some large weapons, such as the German Zweihänder, a metal cover surrounded the ricasso, and a swordsman might grip it in one hand to wield the weapon more easily in close-quarter combat. The ricasso normally bears the maker's mark. The tang is the extension of the blade to which the hilt is fitted. On Japanese blades, the maker's mark appears on the tang under the grip. Hilt The hilt is the collective term for the parts allowing for the handling and control of the blade; these consist of the grip, the pommel, and a simple or elaborate guard, which in post-Viking Age swords could consist of only a crossguard (called a cruciform hilt or quillons). The pommel was originally designed as a stop to prevent the sword slipping from the hand. From around the 11th century onward it became a counterbalance to the blade, allowing a more fluid style of fighting. It can also be used as a blunt instrument at close range, and its weight affects the centre of percussion. In later times a sword knot or tassel was sometimes added. By the 17th century, with the growing use of firearms and the accompanying decline in the use of armour, many rapiers and dueling swords had developed elaborate basket hilts, which protect the palm of the wielder and rendered the gauntlet obsolete. In late medieval and Renaissance era European swords, a flap of leather called the chappe or rain guard