Tessenjutsu

Folding fans with outer spokes made of iron which were designed to look like regular, harmless folding fans or solid clubs shaped to look like a closed fan.
Samurai could take these to places where swords or other overt weapons were not allowed, and some swordsmanship schools included training in the use of the tessen as a weapon.
The tessen was also used for fending off arrows and darts, as a throwing weapon, and as an aid in swimming, like hand-flippers.
Tessenjutsu is still practiced by a few experts in Japan to this day.

Stick Fighting

Two excelent books by Bruce Tegner. He wrote lot of books about various Martial Arts. Most of them were rubish, but these two are absolute gold.

Frank Matsuyama's Kubotan

Frank Matsuyama's 1948 police training manual with Kubotan

The Ultimate Defense Weapon

Nice retro ad