刀
かたな · katana · JLPT N3 · noun
sword
🗡️ katana = kata (one side) + na (blade): a blade sharp on one edge
English borrowed katana straight from Japanese, so you already know the sound. The kanji 刀 started as a drawing of a curved, single-edged blade, and it shows up as the knife radical in characters about cutting, like 切 (cut) and 分 (divide).
刀 — single-component pictograph 刀 (knife/blade)
刀 is a pictograph of a single-edged knife or blade, with the curved stroke depicting the back of the blade and the hook representing the handle. Ancient bronze and oracle-bone forms clearly show a side view of a knife. It still means 'knife' today and serves as a radical in many cutting-related characters.