(■1) Neck - Aikuchi

Japanese: (■1)首 - あいくち

…The earliest bronze sword unearthed was from the Western Zhou tomb in Zhangjiapo, Chang'an. It is about 27 cm long, willow-leaf shaped, and has a neck. Similar willow-leaf shaped bronze swords from the Western Period have also been excavated from Beijing and Baoji, Shaanxi Province. …

From [Weapons]

…Because bronze swords were short, they were probably more practical, and when fighting or facing a small number of opponents in some form, you could simply push forward with the opponent to achieve your goal, meaning that you could achieve high speed with a small movement, making it easier to achieve a practical attack effect. A smaller version of this sword with the same characteristics was the hishu, or aikuchi, which could be concealed and was therefore suitable for assassinations (swords). A shu was a wooden club, often made of split bamboo wrapped in hemp cloth and then wrapped in thread and painted with lacquer. …

From [Swords]

From [Weapons]

*Some of the terminology explanations that mention "(■1) Neck" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…銅剣のもっとも早い出土例は，長安の張家坡の西周墓からのものである。全長約27cm，柳葉の形をもち首（ひしゆ）に近い。北京，陝西省宝鶏からも同様な柳葉形の西周期の青銅剣が出土している。…

【武器】より

…青銅製の刀が短いものであったから，おそらく青銅の剣の方が実用的であって，戦闘中や何らかの形態で小人数の相手と立ち向かうとき，相手に対して，ただ突き進めるだけで目的が達成できる，つまり小さな動作で早い速度が得られるということは，実戦的な攻撃の効果を挙げることが容易であったといえる。この剣の性質をもたせて，より小型化したものが首（ひしゆ）すなわち〈あいくち〉で，隠し持つことができるので暗殺などの目的にかなっていた(刀剣)。　殳（しゆ）は木製の棍棒で，竹を割ってそれを麻布でつつみ，さらに糸を巻いた上に漆を塗ったものが多かった。…