Shinobi of antiquity were instructed to carry six items considered essential inventory for any mission. One of these items was the Kaginawa.
The kaginawa was basically a ship anchor that, according to the Shinobi-Hiden, would be used to dredge things up from water, board ships, pull fences down, and climb enemy fortifications. Within the Shoninki there is also a terse list of uses for the kaginawa, including the locking of doors and binding a person. Owing to its sharp points, the kaginawa also served as a medieval weapon.
In the video below I display a method of constructing a fast-rope for the kaginawa from 850 paracord, and then exhibit just a few of its uses. Once again, the kaginawa was standard inventory for shinobi, so they were likely to have used it for many things that are not apparent to us.