Drill one half of the joint for a t-nut (make sure your holes are centered). Drill the hole a bit deeper than the t-nut, and epoxy the t-nut in place, letting some of the epoxy run down into the rest of the hole's depth. Drill the other half of the joint for a piece of threaded rod (that fits the t-nut and is as long as the depth of the hole), and epoxy it in place. After the epoxy has cured, run a tap through the t-nut and into the remainder of the hole --- the idea is to thread the area beyond the t-nut where the epoxy dripped down. I've used this joint on numerous walking canes, and it is very strong.
Find a place selling fittings for break down pool cues.
Epoxy a nut into a pocket drilled in the end of the staff. Epoxy a stud into a hole drilled in the other section of staff. You can buy "proper" fittings, in brass on-line.Steve