Are There Double-Edged Japanese Swords? — Moroha-zukuri Types and History: Ken, Double-Edged Wakizashi, Warabite-tō

Double-Edged Construction

"Moroha" (double-edged) refers to a blade construction format where both sides (front and back) of the blade have edges. In contrast, typical Japanese swords are "kataha" (single-edged)—where only one side of the blade has an edge and the opposite side is called the "mune" (spine)—whereas double-edged construction has edges on both sides. This format derives from ancient "ken" (straight double-edged swords), and production continues today as shrine offerings, Buddhist implements, and martial arts equipment.

Lineage of Ken (Straight Swords)

Ken is a general term for double-edged, straight-blade swords, and was mainstream in Japan before the Nara to early Heian period (8th–9th centuries).

Lineage:

• Ancient Ken: Straight-blade format originating from China and the Korean Peninsula. Unearthed from archaeological sites in Japan from the Yayoi to Kofun periods
• Shrine-Dedicated Ken: Ritual straight-blade double-edged swords enshrined at shrines. The dedicated swords at Kasuga Taisha and Kashima Shrine are notable
• Kurikara Ken: A design of a double-edged straight sword with a dragon coiled around it, held by the Buddhist deity Fudō Myōō. Produced as Buddhist implements

Edo Period Double-Edged Wakizashi

During the Edo period, with the maturation of samurai culture, wakizashi with double-edged construction pursuing artistic value were produced.

Features:

• Produced for ceremonial, ritual, and display purposes rather than actual combat use
• The beauty of the jihada and hamon were central to evaluation
• Some were custom-made by renowned bladesmiths at the request of daimyo and hatamoto

Representative Bladesmiths of Double-Edged Wakizashi:

• Works by bladesmiths in the lineage of Echizen Yasutugu
• Double-edged works by revival-era bladesmiths of the late Edo period (such as Koyama Munetsugu and Minamoto Kiyomaro) are highly regarded

Evaluation Points for Double-Edged Construction

1. Hamon Symmetry: Whether the hamon on front and back are symmetrical or asymmetrical—evaluation from an aesthetic perspective
2. Jihada Uniformity: The uniformity of jihada grain on both sides
3. Kissaki Shape: The form of the point—blade classification into ken, tanto, wakizashi, and others is determined by kissaki shape
4. Nakago Form: Manufacturing period and school are determined from nakago shape

Modern Double-Edged Production

Today, double-edged swords are still produced by renowned bladesmiths. Modern blades (works by contemporary bladesmiths) in the form of double-edged wakizashi and tanto are:

• Evaluated as "high-difficulty works" demonstrating the craftsperson's skill
• Often custom-made as shrine offerings and temple Buddhist implements
• There are collectors who specialize in collecting double-edged works as a connoisseurship interest

Treatment of Double-Edged Blades in NBTHK Evaluation

NBTHK classifies double-edged swords as "ken," "tanto (double-edged)," "wakizashi (double-edged)," and so forth for evaluation. The evaluation criteria are basically the same as those for single-edged blades—overall assessment of jihada, hamon, and form—though the quality and symmetry of the edges on both sides become additional evaluation points.