My coworker, we'll call her "Jane" is about as sure-footed as a quadriplegic dog. She has this tendency, especially lately, to take the energetically efficient way down flights of stairs.
While humorous, and good for the pocketbooks of local physicians, it does annoy her a bit. Especially when people
around her say things like, "Yar, the ship's doctor did a fine job of puttin' on yer peg leg, sez I." And stuff like that.
For her part, "Jane" now refuses to go down steps without handrails. Understandable, but that does limit her to only about half the steps in the area.
The Personal Handrail solves this problem and others like it. Unfolded, it's shaped like a capital Pi, with rubber feet. Each leg is independently adjustable, with a spring-loaded ratcheting system to allow the legs to shorten and lengthen based on the pitch of the stairs.
Squeeze the handle's contoured grip, while pressing the ratchet release button with your thumb (to prevent accidental release), and the legs adjust as needed at the top or bottom of the flight of stairs. Release the grips, and the legs stay in place. Simply put in place, lean on the handrail as you go down a step or two, and pick it up and set it down again.
For a little added stability, the legs would actually have two feet each, a few inches apart. When unfolding, the feet are rotated from a position parallel to the handle to orthogonal. Feet would rubber-capped, for no-impact use.
When folded, the device would necessarily be as long as the comfortable distance from the step to your slightly-bent hand, so about 3.5-4 feet at the most.
Add a dashing handle at one end, and this could easily be used as a cane on level ground, or perhaps some manner of shillelagh.