If you have never heard of the Cold Steel company, you will find it interesting to take a look at their product line. One of our favorite knives from this company is called the Ti-Lite. 
The Ti-Lite comes in a 4 inch blade that is unbelievalbly sharp from the factory. It also features a quillion that can be snagged on the pocket for one handed opening. You will also find that the this feature is useful for opening off of someone else’s clothing. If you are a cop you will really like this knife because it can be deployed for strikes. Priced around $70, it is a great value.
One additional note. . . I personally have carried this knife for over 2 years. When a Cold Steel product gets dulled, you can send it back to the factory for resharpening and polishing. It only cost about $10 and includes return shipping.