It is extremely important that the sword have good balance (which differs according to the intended use and resulting design of the sword) and good "harmonic balance," or how the sword design carries the vibration resulting from the cutting action. In addition, it is important, (again based on the sword's intended use), that the blade be properly hardened and tempered. Here are definitions of some important terms relating to a sword's performance characteristics:

BL: Blade Length

Blade geometry: The shaping of a sword's blade, both in the profile, and distal views. It is largely responsible for the blade's specific use.

"CoB": The Center of Balance (also known as the "CoG"- Center of Gravity, or "PoB" - Point of Balance) is the point along the blade where the sword has equal mass on either side.

How to determine "CoB": To test your sword, place a ruler or yardstick on edge and move the blade up and down from hilt to point until it balances. Then measure from the hilt to that point.

"CoP": The Center of Percussion is the point along the length of the blade where there is little or no vibration when the blade is struck on an object. When this section of the blade is used in striking, it transmits the least amount of shock and vibration to the user's hand, and also will provide the deepest penetration in a target. A simple test to establish the "CoP" is to hold the sword vertically (with the point up) and lightly tap the side of the pommel. The point in the blade that doesn't vibrate is "CoP."

Forging: Heating the stock piece of steel in a forge (or other heat source) and hammering into shape on an anvil. It is more conservative of steel, but can also be more time consuming. Regardless of how close to shape a piece is forged, a small bit of grinding is still necessary to finish the piece. Neither technique (forging or stock-removal) is better than the other; they are just different methods to achieve the same results.

Hardening (Quenching): Once the forging or stock removal process is completed, a blade is heated to critical temperature (point where the steel is non-magnetic, approx. 1400º F depending on the steel) and then cooled quickly in a type of quench medium. This process hardens the blade, so that it may retain a cutting edge without wearing quickly. Quench mediums can vary depending on the type of steel being used. They include water, brine (salt water), oil (natural and synthetic), and modern quenching polymers.

OL: Overall Length

Stock-Removal: Using a grinder to completely shape a stock piece of steel into a sword. This technique may be slightly faster, but also is more wasteful of steel, as instead of changing the shape (as in forging), it is grinding it away. Neither technique (forging or stock-removal) is better than the other; they are just different methods to achieve the same results.

"Sweet spot": The sweet spot on a sword often correlates to the "CoP" (Center of Percussion- see below), and is the place on a sword's blade which will deliver the strongest blow, without losing power due to vibration.

Tempering: When a blade is hardened, it is very brittle as it comes out of the quench, and if struck on a hard object can actually shatter. Tempering is a thermal heat-treatment where the blade is heated to a temperature below that which the blade was hardened at (usually between 350-500 degrees F), and is held at this temperature for a predetermined length of time. This reduces the hardness very slightly, but greatly reduces the brittleness and the amount of stress in the blade.

Differential Tempering: In this process a blade is through hardened (see below) to a high degree, and then heat is applied to the spine of the blade to make it softer and more flexible. This leaves the edges hard, but the body soft enough to withstand shocks and impacts. This can be accomplished in a number of ways. Tempering tongs are simple tools that consist of a standard set of tongs that have a bar welded to each of the jaws. The tongs are heated and applied to the spine of the blade. This softens the blade, but leaves the edge hardness intact.

Through Hardening: Quenching a blade so that a consistent hardness exists throughout the blade's thickness. With through hardening, there needs to be a compromise between having an edge hard enough to retain its sharpness, and having a softer, more flexible body that won't break when it is used.

Differential Hardening: Quenching a blade so that the edges are harder than the spine or body of the blade. The Japanese sword is the most common example of this type of quenching. The spine of the blade is coated with a clay mixture, then heated and quenched. The thick clay coating on the spine acts like an insulator and causes the coated portion of the blade to cool more slowly (the slower the cooling, the softer the steel). This style of heat-treating is what is responsible for the curvature in a Japanese blade, because only one edge is hardened (hardened steel has a larger grain size than softer steel). There are a number of smiths today that use this method on double-edged sword blades. The hardening on both edges causes the blade to remain straight. The use of clay is also responsible for the visual effects (hamon) in the steel.

Harmonic Balancing: Adjusting the weight of the pommel, and length of the hilt, in relation to the weight of the blade, in order to establish a "Harmonic Node" (see below) within the grip where the user's hand grasps the hilt. The harmonic balance of a sword may be determined through a similar process as that used to find the "CoP." In this instance, reverse the sword's direction (so that the blade is point down), and grasp the grip just above the guard. Again, gently tap the pommel with the heel of your hand. If you feel vibration in your fingertips, move them slightly up or down the grip and repeat. Once you locate the section of the grip that doesn't vibrate, you'll be able to determine the "harmonic balance" of the sword. Different swords will have this second node of non-vibration in different locations. Thrusting swords will require it to be nearer (and sometimes within) the guard, while cutting swords will need it placed around the position of the index, middle, and ring fingers of the user's hand.

Harmonic Node: A point in the sword where vibration is either minimal or non-existent. There are typically at least two of these "Nodes" within the length of a sword, one in the blade (also known as CoP) and one in the grip.

Rockwell hardness: A modern steel hardness scale, with a range of 20-80 points (on the Rockwell C scale). The higher the number, the harder and more brittle the steel is.

Sword Steel

Following are some explanations of the different types of steel used in sword making.

Simple Alloy Steel: This series of steel has a small amount of alloying elements in it and is comprised mostly of carbon and iron. The steel is often designated with a four-digit number (Ex. 10XX). The last two digits vary, indicating the percentage of carbon in the steel. The higher the carbon content, the harder and more brittle the steel. Carbon contents above 1% become incredibly hard, and can be difficult to use in sword lengths, although there are some custom smiths who are very successful with these steels.

Stainless Steel: These are modern steels that contain a chromium content of 8-12% or higher. The chromium gives the steel its stainless characteristics, but is also weakens the grain boundaries in the steel. This causes the steel to be brittle, and, when used in sword-length blades, can cause the blades to fracture very easily when put to use in cutting or even hard swinging. It is a good steel for low-maintenance knives.

Chromium Content: Chromium in large amounts is detrimental to sword steel (as discussed above), but in smaller amounts (less than approx. 5%) it helps in refining the steel grain, and creates a more durable blade. This may seem like the opposite of what it does in stainless steel, but it is a case of "too much of a good thing" can be harmful.

Chrome-Vanadium Steel: This is the preferred steel of Del Tin of Italy. Del Tin manufactures historically based European swords, and is considered the benchmark for production manufacturing. The steel uses both Vanadium and small amounts of Chromium to refine the steel's grain and increase toughness. Del Tin blades have been used in such movies as Braveheart, The Three Musketeers (Sutherland, Sheen, and O'Donnell), and Robin Hood: Prince of Thieves.

Damascus: Damascus properly refers to Indian "Wootz" steel. A type of steel known for its amazing sword characteristics, Damascus blades display an unusual pattern in the steel due to different elements present during the smelting process. This is a bit of an improper term for Pattern-Welded Steel, which displays similar visual characteristics.

Pattern-Welded Steel: This is the process of taking two steels with dissimilar properties and forge-welding them together into a single bar. The bar can then be manipulated by twisting, folding, and other various techniques to give a visible pattern in the steel's surface. Once the bar is forged and rough polished, it is given an etching that brings out the pattern and creates topography in the steel.