By Mike Bartman
It's a Japanese martial arts feather. The Japanese have turned everything into a martial art you see, and have martial arts versions of things like fans, pens (much mightier than the swords!), paper, and, or course, feathers. The full name is really "aikuchiku", but it is frequently shortened to "aikuchi" for convenience.
Use of aikuchiku (Aikuchido) typically ends in a very dynamic pin, with uke helpless, but moving spasmodically, free of any sort of joint lock, but also short on oxygen. Pain is very rare, and this art is suitable for use on small children, even prior to the age of 6, and by people as old as 90 or more.
There are many people who practice this art secretly, but a few famous people who acknowledge, or even advertise, their mastery...Charo is one such. She is known to have threatened to use it on national TV more than once, with her battle cry of, "Kuchi, kuchi!"