Im not a big fanny pack person. It doesnt feel comfortable to me having something like that around my waist.
I live in upstate NY near the PA border. There are coyotes, boar, black bear, and rattlesnakes. I think that the worst fear is rabies. We have had encounters with rabid animals before. Though its obvious the best course of action would be to not be close at all and get out of there, I would like to put myself (with at least a knife) between my family and the rabid animal.
I like the idea of carrying a knife (and I do), for a multitude of reasons, one of which includes self-defense, but that is against people, and is way down on my list of priorities. I sure wouldn't rely on a knife to defend myself against any of the threats you mentioned. We have coyotes in large numbers around us and I've never even considered having to defend myself from one (my dog used to play with one that would come and lay 10' from me when they both got pooped from running). There have only been two documented incidents in recorded history of a coyote killing a human, and one of those was a small child. Not to mention I've been bitten a number of times by dogs (GSD's, Mals, and Pits), and defending myself against them is not something I worry about.
Rattlesnakes are a legitimate threat, but using a knife against one would be sketchy as all get-out. Around where I live we have big cats, and I sure would hate to defend myself against a mountain lion with a 9mm pistol, let alone a knife. Where I backpack in the Sierra, there are on average, more than one black bear per square mile of forest area. But again, saving myself from a black bear with a folding knife or small "non-fighting" fixed blade...no thanks. I'll take a stick or a rock every time if it came to that. So my only reasonable defensive use of a knife would be against humans, and the many I've seen seldom worked out well (or fatal) for anyone involved. I'd prefer a large flashlight to the noggin, or a taser, personally. Speaking of tasers, they work very well on aggressive dogs, as does OC spray (but OC spray sucks on humans). The best (preemptive) self defense in the woods is a good dog. Bears and cats keep their distance from dogs. The biggest limitation is that many nice hiking areas don't allow them.
As for knife recommendations for hiking, a lightweight, weather impervious knife like a Spyderco would be at the top of my suggestion list.