Branch

To start this off I'm going to go with the most basic of weapons possible, a branch. Not the most glamorous of weapons, but readily available and I imagine would be pretty popular during the first few hours of the outbreak. When a few zombies are bering down on you, snapping a branch of the closest tree may be the only option you have.

Durability: Low - Medium
This one is a bit tricky to gauge. A thick green branch cut off of a tree would be able to take more punishment then a dead branch that has dried up, but either way I don't think you're going to get too attached to it. It's a decent enough short term option in a pinch but looking for a replacement should be your next step.

Availability: Very High
Even in the most urban of areas there are usually trees around somewhere. Probably the easiest weapon that I will rate to replace. Find tree… take branch, the end.

Agility: Medium - Very High
Once again this category is a bit tricky to rate. Basically it depends on the branch you take. If you grab a 7' branch that weighs 15 lbs. then obviously your ability to use it is going to be low. That and you're a moron. To sum this up, choose wisely

Cost/Consumables: Low - Very Low
There seems to be a pattern here. It all depends on the branch you pick. I would say that on average most people would pick a branch that would be long enough to keep a fairly safe distance from the zombies, so the danger of using the weapon wouldn't be horrible. Besides that the only other cost associated with it would be the time spent taking it off the tree.

Lethality: Very Low - Low
You will probably be able to take out a few zombies, or at least slow them down long enough to get away. But as I mentioned before I would be on the lookout for a replacement weapon as soon as possible.

Adaptability: High - Very High
It's a piece of wood. With the right tools and if you're willing to invest the time you could turn this puppy pretty much into anything you want. Hammer a few nails through the end, sharpen it to a point, Use it as a spear, roast marshmallows, it's up to you.

Miscellaneous: Medium
The only other benefits I can think of for this weapon would be it's ability to function as a few other items. A walking stick quickly comes to mind, or hell you could even chop it up for kindling if needed.

Final Verdict: Very Low - Medium
The problem with rating this one is how varied the weapon could be. It could range from a rickety old branch that is barely better than using your bare hands, to a decent enough weapon especially with a few modifications. In a pinch even the lowliest branch would give you a slight advantage but it’s still just a chunk of wood you pulled off of a tree. My suggestion would be this. If you find yourself struggling for survival post zombie outbreak and all you have is a tree branch it could do the job short term. However looking for a weapons upgrade would be pretty high on my list of things to do.