As a spearo there is nothing more handy then having a knife strapped to your leg. I use them all the time when spearing and last time I went fishing I had mine strapped to my leg

. There is nothing quite like cutting yourself (and a fish) free in 10m of water with a sharp knife.
If you want a knife for saftey, there is no place safer then to have one strapped on your leg. What good is a knife in your fishing crate or Yak if you are capsized and caught underwater?
Get a good on but still cheap this way you won't cry as much cause it was only 35 bucks.... This is the best bang for buck dive knife I have found.... Sub11D Spearfishing Dagger you can find it on
http://www.spearfishing.com.au/ > Knives > Spearfishing daggers. It actually has a yellow handle But shmeh. It come sharp enought to cut through 400lb mono, Has a nice point for brain the fish (ikijimi killed... make the fish taste better). Has a serrated edge that slices throuhh ropes easy and a normal edge that holds up great. I know it's not made for fishing and you are probably not interested but hey if you are going to use a knife why not get a good one. Plus if you manage to catch that 20kg+ mac of your yak, there is no better way to subdue it than a knive to the brain
Well this is my 2 cents at least you get to see a different side to the coin :/