Hi, Yari,
Thanks for the reply, glad to offer some help. The Korean origin for Japanese forging methods is less likely, as Koryo borrowed alot from Chinese dynasties as well. It might seem likely because Japan & Korea are closer Geographically than China & Japan, but Korean cultural development followed China, as did Japan's. Ancient Korean & Japanese culture is linked in pre-history (as evidenced by linguistics), far before the Iron age.
Your question regarding distinction between Chinese & Japanese swords & swordsmanship is difficult to accurately answer briefly. Technique does differ between the current most popular surviving swordsmanship methods from China & Japan, but bear in mind that method & strategy is partly dependent on the tools (weapons) used. Surviving Japanese swordsmanship schools have developed over several generations in Japan, but the original roots come from China, though direct lineages may be impossible to specifically trace over the course of the last 1,500 years, when the Japanese began using the 2 handed sabre (To/Tachi/Daito/Katana) almost exclusively.
In contrast, the 2 most popular Chinese swords currently in practice are the light, one-handed double-edged straight swords (Jian), and the one-handed "willow-leaf" sabres (Dao, sometimes called "broadswords"); although it is important to bear in mind that the range of different sword designs in Chinese history is incredibly diverse. The diversity of different sword designs pales to the immense diversity of different swordsmanship styles in China, even those still extant.
Even in Japan, with roughly the same design of sword, there are over a hundred different traditional (old) schools of swordsmanship surviving. The Japanese short sabre (Shoto/wakazashi) and great-sabre (No-Dachi) are basically different sizes of the same sword design. The primary function of the 2 handed sabre is its heavy cutting power and deep slashes, intended to sever body parts or open the body cavity, though thrusting is also effective.
The Chinese single handed sabre (Dao) is designed for fast, widely arcing/circular slashing techniques, and allow greater mobility for practical cutting than the heavier 2 handed sabre. The single handed straight sword most popular in Chinese styles for the last few hundred years is a light weapon, not intended for battlefield use, but is primarily a "dueling" sword, where combatants are unarmored. The Jian developed from a heavy, double handed battlefield weapon (very similar to medieval European long swords), but eventually diminished in size to the aristocratic, scholar's weapon common today. It's primary function is thrusting & fast, surgically placed cuts, and requires far more training for effective use than the Dao.
I hope this offers some kind of starting place for the distinctions between Japanese & Chinese swordsmanship. Glad to help someone with common interests.
