need opinions on neck knife for running

[spooky-1]

So I used to cary my pistol when I ran in the AM but since moving to Illinois, this is no longer an option (come on and hurry IL CHL!). SO I have moved to carrying a knife, I want to carry a neck knife and the one I have (kershaw river knife from my kayaking vest) always falls out of the sheath since it is upside down, hanging on my neck. 
SO I need you guys to give me options on what you think are good knives that fit this criteria:

- fixed blade
- hard sheath (kydex, thermold plastic, etc)
- must be able to take ALOT of sweat since I sweat like a hooker in church
- able to attach p-cord and hang around my neck
- most importantly, it cannot come out of the sheath during my run, lots of jarring
- one handed access: grip, pull, ready to go

[Cedar]

I am currently using a knife like that from United Cutlery. So far I like it and it does all the things you are asking. A friend of mine is a Oregon State Trooper and he got one for himself one and he bought me one for a present. I use it when I am hiking.

It fits my hand pretty good, I still wish it had even millimeters more for a tang.

Cedar

[B_Outdoors]

Maybe Blackjack neck knife. Don't have one but it's made from 154 cm so it should work as far as corrosion resistance.

Some other options as far as production knives:
ESEE Izula
ESEE Candiru
Bark River Knives: Bravo Necker 1 or 2
Kabar Eskabar

Not sure about the Bravo neckers steel but the others are 1095 which is a little more prone to corrosion. With occasional care it shouldn't be a real issue. I have the Izula and Eskabar but generally carry the Eskabar more often.
You can get some great aftermarket kydex sheaths from Azwelke. Strongly recommended for the Eskabar. The sheath that comes with it tends to dull the blade. There are several YouTube videos about this.

[Fyrediver]

I like the Becker Necker.  Seems pretty secure.

May also consider carrying a pepper spray?  Gives you distance and a non-lethal weapon for less than life threatening situations.

[Appalachia]

Not sure if you would be interested but I like this knife:

http://www.amazon.com/KA-BAR-Enforcement-Straight-Edge-Knife/dp/B001H53QAI/ref=sr_1_1?ie=UTF8&qid=1341857859&sr=8-1&keywords=tdi+kabar

I am really not into the neck knife thing, I find them hard to access but I carry this one daily.

[Adam Campbell]

I have a neck knife just like this one...

http://www.tuffstuff.us/custom/cart/edit.asp?p=134629

And surprisingly it stays in the sheath through everything. I swim, run, hike, bike etc with this on. I wear it so much I typically have forgotten about it, including a soccer game where I think the refs would have frowned upon someone having a hidden knife under the jersey LFMAO — (as if I don't pull enough dirty tricks behind the ref's backs to begin with).

It has not once come out of the hard plastic sheath even though at first I was certain it would because it didn't feel like a tight fit.

I am going to make a nice paracord handle for it and upgrade the cord that goes around the neck to some 550 cord as well.

Can't beat the price on this one!!!

I've used this so many times it is invaluable and I keep it in the same mental OCD state as my phone, keys, and wallet are now when I go anywhere.

[murf]

Take a look at the mid tech Fred Perrin shark. It's a smaller variation of his la griffe design. The finger ring and pistol grip render it nearly impossible to disarm and quck to deploy. The shark is made from 440c, and I believe it is/was imported by Boker(made in France). Examples are for sale on Ebay and Amazon. If you're interested, there is an Amazon add on my blog.

[ridge rover]

This is my neck knife.
http://www.tek-tite.com/src/product_info.php?id=3071


Its small but has saved my butt when my other knife was home on the dresser, or misplaced at the last place I put it!


It has a monster 1.5 inch blade!
http://www.amazon.com/Tekna-TEK-XE-XTRA-EDGE-2-Inch-Keyring/dp/B007VN2HO6/ref=pd_sim_sbs_sg_1