Nothing works on everyone every time, but anything is better than nothing. It's all about increasing your chances imho. Weapon (external and/or body) + sound training = force amplifier.
Say your chances were 1 in 10 without force amplification and 3 in 10 with force amplification. You're still likely to get annihilated but if escape/deescalation fails then your chances are now 3 times better than before and growing as you improve. I say, that's massively better chances than lotto!
If you can make that force amplification thing a hobby you actually enjoy then you're losing no time and no resources but only getting advantages from it. You don't train any of this stuff for that one moment 10 years in the future when evil ninjas come to kidnap your family.

But if evil ninjas do come and kidnap your family, you don't want to end up being that bum with the cardboard sign that reads: "Ninjas kidnapped/killed my family. Need money for kung fu lessons".

On average, it takes 10 years for ninjas to show up and mess with you, so if it takes only 6 years to learn some skills to potentially stop them, that's a good deal.

Hi everyone, I'm back. Remember me? The OP? ;-)

This thread has taken on a life of its own, with everyone making valid points. But I think it all boils down to this...

...so I've decided to start carrying something. Not a baton, because after doing some research, the laws in my state are very wishy-washy on whether or not I can carry one. Instead, I'm going to invest in...

...strong light to blind an attacker and hard enough to crack 'em in the head/leg/whatever if I absolutely need to. Like I said in my first post, I don't want to hurt anyone, but if it's going to be me or them, I'd rather it be them.

ChaunceyK, I just noticed there was a little mixup with quotes in your post, the second quote refers to iippo's post about the Mag-Lite, here it is:
http://www.gog.com/forum/general/nonfirearm_selfdefense_weapons_not_gaming_related/post74

Btw, I agree with both of you that a good old Mag-Lite is a fitting choice for your demands. The LED Mag-Lite shines much brighter than the one with regular bulbs, big difference but also more expensive. I have a medium size Mag-Lite that fits 2 batteries, it shines just as bright as the longer one with 3 batteries and it's a lot handier, a lot less heavy too. Less intimidating but you can be much quicker with it. I've used the longer Mag-Lite as well previously (normal use, not cracking skulls) but never liked it much.
I don't really take such heavy things with me anywhere nowadays, a small Petzl headlamp is all I need for illumination.

The closest thing to a weapon** I carry outside is a pair of Kerma Nepalight 8 trekking poles when I go hiking in the mountains, I guess those trekking poles could be used to fend off very angry cows -possibly humans as well- but I haven't had such a situation, yet. Avoiding eye contact works well with animals. Either way, trekking poles are ultralight and expandable, have a good grip and are legal everywhere. And you can use them as tent poles.

**not counting Swiss Army knife, that's a tool and would take too long to unfold, plus you'd need both hands to do so. Also, too dangerous anyway, much can go wrong. However: You can use a pocket knife to make weapons, let's say you're in the forest and all you have is a little knife. You can quickly upgrade yourself into a primitive spearman by shaving a wooden branch to a sharp point.
Or you could pick up an animal bone and re-enact the Dawn of Man: https://www.youtube.com/watch?v=qtbOmpTnyOc

Darn.

When I saw you'd quoted awalterj, I was confident you'd opt for a two-handed sword.

In any case, consider reading Snow Crash for badass deliveryman inspiration.

Dang quotey-things...thanks for the heads-up, I meant to give iippo credit! Fixed!

And thanks for the rest of your post, too. :-)

IGNORE all previous posts.

What you need is the weapon you see at 0:23 of this video clip.
https://www.youtube.com/watch?v=q7heVIEyvQ4

I have no words for this.

As others recommended try for a martial art. Also equip a level head.