The samurai used various weapons, but the katana is the weapon that has come to be synonymous with samurai, metaphorically speaking. Bushido teaches that the katana is the samurai's soul and sometimes a samurai is pictured as entirely dependent on the weapon for fighting. They believe that the katana was so precious that they often gave them names and considered them as part of the living. After a male bushi child was born, he would receive his first sword in a ceremony called mamori-gatana. The sword, however, was merely a charm sword covered with brocade to which was attached a purse or wallet, worn by children under five. Upon reaching the age of thirteen, in a ceremony called genpuku, a male child was given his first real weapons and armour, an adult name, and became a samurai. A katana and a Wakizashi together are called a daishō (lit. "big and small").

3 sams with weapons

samurai with assorted weapons

The wakizashi itself was a samurai's "honour weapon" and purportedly never left the samurai's side. He would sleep with it under his pillow and it would be taken with him when he entered a house and had to leave his main weapons outside.

The tanto was a small knife sometimes worn with or instead of the wakizashi in a daishō. The tanto or the wakizashi was used to commit seppuku, a ritualized suicide through disembowelment.

The samurai stressed skill with the yumi (longbow), reflected in the art of kyūjutsu (lit. the skill of the bow). The bow would remain a critical component of the Japanese military even with the introduction of firearms during the Sengoku period. The yumi, an asymmetric composite bow made from bamboo, wood, rattan and leather, was not as powerful as the Eurasian reflex composite bow, having an effective range of 50 meters (about 164 feet) or 100 meters (328 feet) if accuracy was not an issue. On foot, it was usually used behind a tedate, a large and mobile bamboo wall, but could also be used from horseback because of its asymmetric shape. The practice of shooting from horseback became a Shinto ceremony known as yabusame.

In the 15th century, the yari (spear) also became a popular weapon. It displaced the naginata from the battlefield as personal bravery became less of a factor and battles became more organized around massed, inexpensive foot troops (ashigaru). A charge, mounted or dismounted, was also more effective when using a spear rather than a sword, as it offered better than even odds against a samurai using a sword. In the Battle of Shizugatake where Shibata Katsuie was defeated by Toyotomi Hideyoshi, then known as Hashiba Hideyoshi, seven samurai who came to be known as the "Seven Spears of Shizugatake" played a crucial role in the victory.

The later half of the 16th century saw the introduction of the teppō or arquebus in Japan through Portuguese trade, enabling warlords to raise effective armies from masses of peasants. The new weapons were highly controversial. Their ease of use and deadly effectiveness was perceived by many samurai as a dishonorable affront to tradition. Oda Nobunaga made deadly use of the teppō at the Battle of Nagashino in 1575, leading to the end of the Takeda clan.

After their initial introduction by the Portuguese and the Dutch, the teppō were produced on a large scale by Japanese gunsmiths. By the end of the 16th century, there were more firearms in Japan than in any European nation. Teppō, employed en masse, largely by ashigaru peasant foot troops, were in many ways the antithesis of samurai valor. With the establishment of the Tokugawa shogunate and an end to civil war, production of the guns declined sharply with prohibitions to ownership. By the Tokugawa period most spear-based weapons had been phased out partly because they were suboptimal for the close-quarter combat common at the time; this combined with the aforementioned restrictions on firearms resulted in the daishō being the only weapons typically carried by samurai.

In the 1570s cannons became a common part of the samurai's armoury. They often were mounted in castles or on ships, being used more as anti-personnel weapons than against castle walls or the like, though in the siege of Nagashino castle (1575) a cannon was used to good effect against an enemy siegetower. The first popular cannon in Japan were swivel-breech loaders nicknamed kunikuzushi or "province destroyers". Kunikuzushi weighed 264 lb (120 kg). and used 40 lb (18 kg). chambers, firing a small shot of 10 oz. The Arima clan of Kyushu used guns like this at the battle of Okinawate against the Ryūzōji clan. By the time of the Osaka campaign (1614-1615), cannon technology had improved in Japan to the point where at Osaka, Ii Naotaka managed to fire an 18 lb (8.2 kg). shot into the castle's keep.

Staff weapons were also used occasionally by samurai, the being the most famous example of this. It could also be made stronger by being covered with steel rings, an example being the . A club called the Kanabo, which was coated in steel studs, was more frequently seen in mythology than in reality. However, when actually used, it would be a deadly force on the battlefield.