They are interesting. A local antique shop had one with an 18th century hollow ground triangular section smallsword blade, but unfortunately I was out of sword moneys again and when I went back to make an offer a little while later it had been sold. I should have taken pictures.
Since I don't have much in depth knowledge myself I will leave a couple of videos by Matt Easton:
Swordsticks - the walking cane with a sword blade inside
SWORDSTICKS! Use in historical newspapers & the law
EDIT: Oh and also, this Chinese example:
Exceptional Qing Sword Cane