nigel wrote:it seems that there are many more old Japanese swords than western ones that have lasted in good condition. Is this correct? And if so, how come?
Yes, I suspect because there are many westerners that enjoy the pursuit of Musō Jikiden Eishin Ryū (MJER) Iaido and other forms of the Art of the Japanese sword, (I did until knee issues, after a scoot accident - as all Iaido begins with seiza, a kneeling position). Modern western swords, made of T10, L6 or 9260 are best for actual cutting use, I still use a Japanese made Iaido for actual practice of this ancient art (which is not a real sword, un-sharpen, but retaining the real koshirae, weight and characteristics of a real shinken).
It is considered a sin to test or cut with a nihonto such as these, (there are strict protocols when handling koto nihonto).
Swords like the one above along with another 500+ year old one I own are stored and cared for religiously, for like firearms, when purchased wisely and cared for properly, they do nothing but appreciate in value over time - especially when properly paper'd and like the one above which was last polished and sayagaki'd in October 1940 by the premier polisher in Japan at that time, Honami Koson. (a sayagaki is an appraisal written on a shirasaya, the wooden sheath designed to protect the sword, as most are never kept in their koshirae, the scabbard, handle and furniture, which is generally kept seperately)
There are also a lot of fakes - best to have someone ya really trust when considering the purchase of these ancient items, as real nihonto are pricey dependent on their bona-fides.