TimoS
Master of Arts
I think it really depends on the kata. Some kobudo kata are probably quite old, some are quite new. As I've understood it, e.g. nunchaku kata are all new, but I wouldn't be surprised if some of the bo kata are old.As I understand it however, it is generally accepted that Okinawan Kobudo Kata are much younger than Okinawan Karate kata.
Kobudo as a separate system is much more recent, even more recent than the creation of karate ryu, but I think the actual kata were preserved by masters. Taira Shinken and Matayoshi Shinpo (or was it Shinko, I always confuse the father and the son) were the two (main) persons responsible for collecting all the various weapons kata under their systems from different masters. They also created new kata, but as I understand it, the core of their teachings was gathered from different masters. One master would know e.g. a bo kata, another might know a sai kata and so on.