Some more (possibly) Chinese cha/sai:
Group of Highbinder weapons including a sai: http://amst312.umwblogs.org/2009/01/29/the-highbinders/
Further to my earlier comments on trying to identify the origin of a particular sai, Okinawa was a major trade centre, connecting China, Korea, Japan, and the Philippines. A lot of trade went through Okinawa, with Chinese goods proceeding to Japan and the Philippines, and Japanese goods going to Chinese and SE Asia. Given domestic Okinawan iron production being what it was (I've seen it described as "absent"), a lot of "Okinawan" iron goods may well have been imported in the finished state, rather than being locally made.