How do i turn an unbrella into a sword stick?

Sword sticks where traditionally made with a sword hidden inside an every day object, often a cane. I would love to turn my old umbrella into one but don't know how....not even the foggiest.

If it's one of those spring operated umbrellas then I think I can manage that. Remove the umbrella handle far from the button you push. Weld or epoxy your sword to the handle. Insert the sword and adjust the umbrella handle back to its exact original position, and tape it back with an identically colored tape. It's a crude method, but the crudeness of the tape allows you to pull out the sword if you apply ample force. Just make sure that everyday use does not have enough force to force the tape loose and open the sword stick. Good luck!
assuming that you  are talking about a standard umbrella (one with a curved handle) then one could simply remove the handle, hollow out the straight "shaft",if you will, connect a blade to the removed handle,making sure it is apropriate length, and fitting it to the hollowed "shaft"(sheath) with some form of a holder i.e. a strong magnet and a metal area in the sheath, a wedge or a small bump and hole, anything that would keep the blade from falling on its own, I hope this helps.