AJ thanks for the response.
Just wanted to update on what I found.
I have decided on the knife I am getting for emergency use. The Columbia River Knife & Tool(CRKT) Bear Claw. This knife is made specifically for cutting quickly. It is a fixed blade, only 4 1/4" total length. It comes in 4 models, straight edge, serrated edge, serrated edge with a blunt tip and an Emergency Rescue Model, which is the serrated knife with a blunt tip and hig vis orange handle. The blade is stainless steel. It comes with a high impact plastic sheath that it locks into and can be released with a thumb push or can be pulled out with a sharp pull. The sheath can be secured by clip or several other methods. The price is reasonable as well.
http://www.crkt.com/bearclaw.htmlThis company also makes other knives the Hammond ABC and the MAK-1. They are significantly higher in price.
I also came across several other brands and makes that make dive, PFD or rescue knives that will work. They were all significantly more expensive than the Bear Claw and did not have good ways to carry them and secure them until needed(which is hopefully, never).