Here's a couple of links re: knife laws:
http://www.knife-expert.com/sta-law.htm
http://www.realpolice.net/forums/ask-cop-112/63366-ohio-knife-laws.html
http://answers.yahoo.com/question/index?qid=20080604164352AAxJhj2
Best bet is to ask your local district attorney's office via letter (something written).
Usually state laws will be modified or added to by city or municipal governing bodies (within the original law).
Frankly, I would say a knife is not the greatest weapon, or even a good weapon, for self-defense.
Just look at it re: stopping power, post-incident impressions (stabbing/shooting someone -- emotional judgment), as well as actually owning what looks like a small shiv, etc.
Still better than nothing though assuming you understand all the repercussions and have some skill/practice under your belt.
The LDK is just that, a last-ditch knife meant to be hidden in obscure places - hanging around your neck under your shirt is not the best use.
Try looking up the places people have placed razors on their person or on objects for example...
I bought one when they first come out, and I've no confidence in the sheath it comes with. The knife itself is VERY thin and not very comfortable in just about anything but a index/thumb pinch grip which is less than secure. I think the Shivworks Lil' Loco is a much better design but... again, the name and "implied intent" behind owning and carrying one must be considered.
Your brain and your body are your best self-defense tools.