Hotsure (ほつれ) is a term used in the context of Japanese swords. It refers to a feature that appears along the edge of a straight tempered blade (Suguha). This feature appears as a thin line of ""Nie"" (沸) - the visible particles of hardened steel - that runs along the grain of the blade, resembling a frayed thread.
The term ""Hotsure"" translates to ""frayed"" in English. It is named so because the feature appears as if the straight blade is fraying or unraveling, creating a unique visual effect.
This feature is mainly seen in the works of swordsmiths from the Yamato tradition. The Yamato tradition is one of the five main traditions of Japanese sword making, and it is known for its distinctive straight tempered blades.
Therefore, ""Hotsure"" adds a unique and interesting visual effect to the blade, enhancing its overall aesthetics and value.