I think everybody who has already posted answers or solutions here have covered the options very well, so I won't be redundent except to say that I think Cold Steel's Bushman is a heck of a good knife for the money and for mounting on a staff or stick. (Anybody know why they quit making the Mini-Bushman? Wish I had bought a couple now.)
Anybody here know what the bayonet from one of those Chinese SKS rifles looks like? Our brilliant bureaucrats in the BATFE decided several years ago that it would no longer be acceptable to sell or own Chinese SKSs with the folding bayonet still attached. So at one time there were probably tens of thousands of those bayonets that had been taken off the rifles to make them "legal" to sell and own. (I've never heard of anybody being prosecuted for ignoring this rule, though.) These were "spike" type bayonets with a tang about half an inch in diameter and about three inches long, and with a nice sized hole through it near the aft end. I have thought about drilling an approprate hole into the end of one of my rattan walking staffs so I could insert the tang of a SKS bayonet into it and then cross pin it in place, possibly with a clevis pin so it could be easily removed (dismounted) when you wanted to.
Now, what I HAVE done is to make up a few "pikes" using an SKS bayonet permanently mounted in a hardwood rake handle with epoxy. You can go to your local hardware and building materials store and pick out a good, straight-grained hardwood, bow rake handle that's about 5 feet long for about $10. It comes with the correct size hole already in the end and a steel ferrule around it to reinforce that end. I just poked some epoxy down the hole in the rake handle, then inserted the tang of the bayonet into it, and tapped it all the way in using a piece of scrap wood or a lead ingot. Wipe off the excess epoxy that squirts out, set it upright to harden overnight, then you're good to go. Go do what, you might ask? Well, it's good for picking up trash along the road where a few jerks throw their fast food residue out as they drive by, and it's good for poking whatever slow moving critters might be walking or slithering around where you'd rather they not be. And if any of you know how a flounder gig is used (to pin the fish to the bottom in very shallow water), this gizmo should work well for that, too. At one time the Chinese SKS bayonets were as cheap as $1 a pop, so I bought several of them back then, but now they cost maybe $4 or $5 apiece in case you want one. They are not hard to find.