Tekko

The Tekkō (鉄甲^?, lit. "iron", "armor"), which originated in Okinawa, Japan, falls into the category of a "fist-load weapon". By definition, a fist-load weapon increases the mass of the hand so that, given the physical proportionality between the fist's momentum and its mass, it increases the force the bearer can deliver. Some fist-load weapons may also serve, in the same manner, as the guard on a sword, to protect the structure of the bearer's hand.

The Tekko evolved after five stages of development. The first, called the "Yawara", consisted of nothing more than a stick or rod, held in the inside the hand. The "chize kun bo", a stick with a loop of rope, which the user could attach to the hand for control, came second. Third, the "Teko" resembled the "chize kun bo" but, rather than a rope, had a sharpened wooden extension of the stick, which fit between the first or second finger. An Okinawan tool to help fisherman weave, or haul in their nets without cutting their hand on coral, or a long hairpin used by Okinawan Bushi called a "kanzashi", quite possibly served as the inspiration for this design. The Teko appeared in hardwood form, and as soft molded metal so as to greater increase the mass of the hand.

The fourth stage, or "Tek Chu", allowed for increased function over its predecessors in that it "extended beyond the clenched fist", "a distinct advancement in the evolution of fist-loaded weaponry". The design consisted either of a wooden stick carved with a wooden extension with a finger hole, or of a metal rod with and metal finger ring. The bearer held the rod in hand, with the ring around a finger. The Tek Chu often included a carved point or a metal spike protruding from the ring.

Use of the true "Tekko" per se started with the "Horseshoe Tekko". Because weapons were banned in Okinawa, the Okinawans sought to put otherwise agricultural implements to martial use. "The use of the horseshoe appears to have originated when Bushi in Okinawa used the shoes of their horses as make-shift weapons to defend themselves against surprise attack. "They simply put a horseshoe into the hand to punch with" (Ryukyu Hon Kenpo Kobjutsu Federation). Held as a "U" with the hand in the middle, the two ends extended outwards.

Practitioners also tied two horseshoes together directly facing and overlapping each other. This design provided greater hand mass, and defensive guard, but resulted in larger weapons, not easily concealed, and more difficult to learn. The improved horseshoe tekko featured the two horseshoes welded together. However, the popularity of the horseshoe tekko faded, as attention turned to the smaller, more concealable horse stirrup.

...
Wikipedia