Swords are made from two different harnesses of steel giving them both strength and flexibility. Low carbon content means softer, more flexible steel, where as higher carbon concentrations makes harder, stronger steel. The hardness of steel depends on the carbon content of it. When cooling, the two types of steel cool at different rates making them curve. The swords were hand made by the most skillful craftsmen in Japan that also had good moral values, because an evil craftsmen makes an evil sword.
Spears were made of stout oak shafts in which the tangs that were sharp on both sides sunk into.
purpose of the symbols was also so others could identify the samurai, symbolize his bravery, and scare away his enemies
whole plates of armor were made out of small scales called lamellae- shiny lacquered leather or iron, copper, and other metals; sometimes silk or rawhide strings connected lamellae horizontally, and were put together vertically by thick silk
color and patterns of the silk identified the samurai or reflected his personal taste