I have been using 2 for a number of years. The BFK goes on the inside of the calf. Its most important feature is the heel, which makes an excellent hammer. My kids also think it too cool to leave on shore (it is my original from 1980). It is great if I want to smash a snail or clam to attract fish. The second is a 3" titanium coated blade that I wear inverted on the quick release of my BCD weight pocket. When the weight is in place and tightened down, the handle lays flush on the weight and extends out about an inch. This is the blade that I use for cutting. it was cheap ($12) from an online store and is considered disposable (I have lost one in the last five years, but found a couple of them). This year Santa bought a Trilobite to go on the other side of my BCD. Its function is as a back-up to the 3" and for cutting multiple lines.
I had a kid (20 something) at a dive picnic tell me that he would never want a pointy tipped BFK like mine (I was cutting the watermelon with it) because the tip would break off and was too big to be useful. I had to laugh because the knife was older than he was. I also pointed out that I was cutting the watermelon because no one else had a knife big enough for the job. Love to see some of you guys try to gut a watermelon with a Trilobite or EMT shears.