Blade

Kallal (칼날) is the Korean word for the blade of a knife or sword. A Korean learner's dictionary defines it as the thin, sharp part of a knife that cuts. It is formed from 칼 (kal, «knife, sword») and 날 (nal, «edge»), and Wiktionary traces it to a 1481 text.

Kumdo is practised with the bamboo sword (jukdo, 죽도), which has no real edge. One kumdo school's page says the blade is only suggested as the side of the jukdo opposite the spine string (deungjul, 등줄). A Korean kumdo lesson describes the four bamboo staves as follows: the top is the spine, the bottom is the edge, and the two sides are the ho (호), the line between spine and edge.

• The jukdo is held with the deungjul facing up.
• A valid strike must land between the leather tip (seonhyeok, 선혁) and the middle band (junghyeok, 중혁). This zone is called gyeokjabu (격자부).
• Beginners should be taught which side is the spine (kaldeung, 칼등) and which is the edge. A strike that does not keep the edge line correct does not count as valid.
• The Korean Kumdo Association's textbook (대한검도회) asks practitioners to keep the direction and path of the edge correct when striking. It also asks instructors to teach edge direction when gripping the sword.