Permission from David Esteban Guzman to repost and edit this.
There are three terms on the art of Japanese sword that can be found practically in all combat classical schools in Japan, these three terms with more or less influences derived from three main sources of masters and documents of transmission from the currents of combat that left their mark in the history of swordsmanship and Kobujutsu (古武術). These three currents were Nen-ryu (念流), Kashima-ryu (鹿岛流) and Kage-ryu (影流).
These three basic terms are in use in the currents of Bujinkan Ryu-ha (武神馆流派) and they can help us to extend the perspective of how the Japanese sword was in use for protecting the body in the combat.
The first term is uke-nagashi (受流), consists of two characters. The first is uke (受), ukeru verb, means “to receive”, “get”, “subject”, “delete”, “test”. The second ideogram, nagashi (流), nagasu verb, meaning “to spread”, “let’s run”, “pour”, “spread – disseminate”.
It is to aspire for the weapon of the opponent (yari, naginata, shinken, nodachi, kodachi, etc.) to slide, be left to run on our sword with the aim to absorb the assault and not damage ourselves or our sword. There are several basic ways to perform this technique, but everything lies in the union of two actions, the first action is to synchronize our weapon with the enemy weapon at a very precise distance, the second action is to move your body weight in the proper angle to avoid any attempt of cutting or blow absorbing the enemy’s attack. Uke-nagashi is a type of protection that allows a movement of continuity, to deflect or accompany the cut or assault of the enemy with our sword.
The second term is Uke-tome, the verb “tomeru” (止める) in Japanese, which means “stop”, “stop motion”, is a “stop”, is a hit blow in a way of blockade. The third term is Uke-kiri, cutting block. In the first two terms can be used depending on the situation, the mune (back of the sword), the sides of the blade or the tsuba (hand guard of the sword) to protect us from the attacks of the opponent.
In the term Uke-Kiri, the ha (edge) of the sword is used to defend the aggressive attacking of the the enemy, but it is important to note that if we divide the blade into three parts, the first two parts of the sword starting for the tsuba (hand guard of the sword) are the best placed to repel the attacks of other weapons, the last part of the blade which shelter the largest area of cut, the nearest area of the boshi, the kissaki, and the part that is the most involved of cutting in the blade, is vital to keep operational and undamaged (nick or break the blade). It is a necessary skill, flexibility and high synchronization to block a blade attack with our sword and not damage the blade or harm ourselves in trying, we’re talking about masters or practitioners of high degree of practice.
It is one thing is to use a bokuto (wooden sword; 木刀), another a iaito (dull blade for the practice of iaido; 居合刀), and another more different is a shinken (real sword; 真剣). This is directly connected with the techniques of the body to receive, the Ukemi (受身), where the flexibility of body and mind is vital, the body is made primarily of water, for this in the practice is very important the understanding of the emotional and mental tension and his link with the body attitude.
The participation of the mind and body in communion is the most important, the union of mind and body is an attitude adjustment or adaptation through a profound physical and mental flexibility, in this lies the art of the masters, from the unit to the multiplicity.
This masters of Kobujutsu (古武術) used the art of Musoku No Hô (無 足之法) for develop these blocking techniques and the ukemi, the art of concealing the weight of the transfers of the movement, the art of maintaining the vitality and youth of the bones in old age.