Typically, blade length of a combat knife is about 150-200 mm (6" to 8"), and blade width is about 30-60 mm (1.2" to 2.4"), and these dimensions are optimal for cutting. Blades of modern combat knives are made of high quality steel, which provides first rate performance in flexibility and durability and enables a superior sharpening of the cutting edge. Usually, the sharpened edge is one or one and a half-sided.
Weapons such as stilettos and dirks have not been used since the late Middle Ages when muskets replaced swords and rapiers. Those knives were ideal to pierce chain armors, but their cutting ability was weak. Currently, combat knives should meet high requirements: the damaging effect should be equal to that of a firearm, and the objective is to injure but not to kill the rival.
As for the shape of a blade itself, those blades which are semi-rounded are considered to be the most efficient because of their optimal ratio of cutting edge length and knife portability. Today, the body of a modern fighter is protected by special clothing and various shields, which make him almost invulnerable to stab injuries. The areas of potential damage include only the neck, forearms, and face so it’s necessary to consider the blade length to handle length ratio that provides the most precise balance of a knife so as to target the vulnerable areas in a close combat.