Hey all, thank you for the amazing responses! My camera's batteries are charging while I'm at work, and I will do some photos and planning later in the day.
The short versions is, I'm currently considering doing a light wire wrap and THEN putting a metal band over that, to minimize the damage to the wood.
I would say your best bet is to use strips of metal and then nail it onto the staff. It really depends on how the wood is splitting. A sideways crack needs a lengthwise piece of metal. A lengthwise split would need a metal clasp. Of which you should probably use 2.
I really don't think the wood will survive the nail, but that was also my first thought
It's not splitting yet, but the botton is starting to get damaged from the thumping against ground as I walk around.
TEST EVERY TECHNIQUE ON SOME OTHER CHUNK OF WOOD FIRST.
That's my advice.
I'm so happy you suggested that, I actually didn't think about it... there is plenty of wood around that same forest.
Out of these options I'd try going for the wire, copper for preference, as it'll be easy to work with. I'd combine it with the drilling of a pair of small holes at whatever location you're going to apply the wire, the feeding through one of the holes and making a knot, so you can pull the wire really tight when wrapping the staff. Also copper, although relatively expensive, will be easy to finish i.e. remove any excess sticky-out wire is easy with wire cutters, hammering and maybe a small file.
Another, uglier, option that occurs to me that maybe be the easiest and most effective would be to make a cap for the bottom of the staff (where it's going to see the most stress) by finding a short length of widish copper pipe (scrapyards, building&plumber supply places or a hacksaw, nighttime and localized utilities outages are the easiest option), fitting it over the staff with some excess peaking out over the length of the staff and then hammering to fit/to make a cap. Also, IIRC, while soft relatively soft copper work hardens, which should help. Could possible be combined with the wire+holes for extra sturdiness.
It might be helpful if you could post a pic of the staff so we can get a better idea of it. Also, randomly found staves, staffs and assorted sticks are cool. Some people may laugh at you when you say this, but luckily you already have a big stick on hand.
Thanks for the detailed advice! Wire is the easiest, but I am really wanting the look of metal bands. I don't need to improve the grip, but the rest of the staff could use some support.
I say go with the ring for the sake of quality, but make it something soft so that you can crimp the bottom with a hammer and a sturdy surface's edge. Especially if you haven't done it before, the wood will scorch a good deal, creating some charcoal, and that can make a looser fit than you expected. Keep in mind that unless you put some brads or small screws in, it's probably going to develop a certain amount of wobble after a while, but that will go away if the wood does start to edge towards splitting - just part of aging a staff of this sort.
And yeah, if you can, practice with a piece of similar dimensions. You can only do this so many times on your precious stick, after all It'll help you avoid the 'oh fuck' response you get when you're first starting to work with hot metal and give you a better idea whether it will actually work for the dimensions of the band and the wood. It probably doesn't need to be glowing-hot, mind you. Even below those temperatures metal will expand enough if the dimensions are thin. Consider shaping it into something more round so that you have a closer standard to go by when looking for a band - the more precise the fit, the better it will hold up under wear. You also want it -past- the very edge of the staff, which will let you put in a small nail if it does end up slipping loose before the end can bloom out from hitting the ground.
For materials I suggest considering bronze if you can find it - it'll have a higher heat expansion, and is less likely to deform with the wood. Aluminum is also nice because it holds a paint extremely well, which is easy to make decorative patterns for using a wax stencil technique. Just be careful as it's surprisingly easy to melt. Here's a list with specific alloys to keep a watch for http://www.engineeringtoolbox.com/thermal-expansion-metals-d_859.html Plutonium being, of course, ideal for your purposes. It's all up to personal taste and the amount of practice you want to put into it - you could even use a mild steel, though that will be both tougher to crimp and require more heating.
Thanks for the awesome advice! I'll need to do way more thinking...
EDIT: Wait... plutonium? Isn't that radioactive and also prohibited?
And yeah, I'll have a few photos up later today