i would be very interested to if anyone can explain a way to do it. it might help me too. for months ive wanted an assassins creed retractable wrist spike lol..i cant come up with a way to make it work though

Seems to me the USSR had something like that in the form of an umbrella. As the person walked by you, he "accidentally" swatted you with his umbrella. What he did was activate a spring in the tip, that pushed a needle into you. The needle injected a tiny metal ball that had a slow release dose of ricin, that would kill you several days later.

you can make it along the lines of a machine gun bolt. the spike would have a small bolt or handle attatched that stuck out the side. the cane would have a long groove or channel along the shaft and two short grooves at right angles, one at each end. flip the bolt up out of the short channel and the spike slides out. flip it down at the other end into the other short channel and it locks in place. add a spring inside to the back of the spike and you have your 'switch cane'!

Thanks for all the ideas, I like paleoarts the best, using a rifle like bolt mechanism. I want it to use in conjunction with hunting with an eagle. You just never know what they may catch, and if it is a predator, there is a real danger from getting hurt by either critter. With a spike on the end of my stick I could control it without the danger of getting hurt too.

Lowinger. Check your legalities mate.   In Aus what your talking about comes under the swordstick and switch blade laws, in other words they're illegal as hell.
Having said that I'd suggest you find a narrow metal tube that the spring from a full sized auto opening umbrella will fit. Grind your spike so it has a shoulder that rests against the spring and a sear on the front of the shoulder that is held by a lever or button. Fit an end cap (with a central hole for the blade of course) to the tube to hold everything in place and fit the whole unit into the end of your stick, or just make a sword or dagger cane.
Perhaps one of those walking sticks with a screwoff handle could be modified by drilling out enough space for the blade then fixing the tang in the handle so that when you pull on the handle out comes the blade.  I don't recommend doing it though. It'll trip almost every concealed weapon rule in existence!! Typhon

That isn't a pike, its a spear. Whoever made the site needs to do more research.

One option could be a simple spring loaded blade in a tube, which has a hole through the shaft. A pin is pushed through the hole, with the other end of the pin having a protrusion perpendicular to it, which rotates into a slot held by a one way hinge (really easy to make, just have it slightly higher than the protrusion with another piece that goes over the metal piece attached to the hinge). Getting the spike back in is trickier, but if you have the one way hinge door screwed in just un-screw it and take out the protrusion. Then screw it back in, pull out the pin, and press down the spring loaded blade.

The entire process of getting it out is pushing a button, then pushing and twisting a pin, which should be fast, which is critical. Getting the blade back in takes longer, but that is pretty much necessary.