iron-ribbed fan
A folding fan with iron ribs, used historically as a defensive weapon or for signaling. Often associated with samurai and martial arts.
In a period drama, I saw a scene where a samurai kept an iron-ribbed fan hidden in his breast pocket.
martial art using an iron fan
Compound of 鉄 (てつ, 'iron') and 扇 (せん, 'fan'). The reading てっせん results from the assimilation of つ to っ before せん.