My favored karambit is something like the PS, made by Strider Knives, in collaboration with Steve Tarani. I did not buy one of the semi-production PS Karambits, before Strider Knives went away, but did buy two hand-made MSC versions, one titanium and one Stellite. In actual practice, I have carried a Tarani Masters Model Karambit folder, daily, since about 2004. Steve Tarani, himself, has stated that karambits of this size are back-up weapons.
“Fighter” implies something a bit larger. The Randall 1-7 seems to be an ideal “just right,” or nearly so, a balance of portability, utility, and enough blade length to easily reach the vital bits inside a human body. I really like the Randall 1-7, and have two of them. Handling seems quite intuitive. The Randall 14 may be a better idea, with its beefier tang. I have attended a very small amount of FMA-based blade training that used dull-edged replicas of the Randall 1-7, but it has been quite a while ago.
I have an Ontario-made Bagwell Helle’s Belle, and while I enjoy handling it, I am not sufficiently skilled to find its handling to be intuitive. I would be less a danger to myself if I used something more like a Randall 1-7, if desperation compelled me to fight, using a knife.
At Blade Show 2015, I bought a Kasper Scorpion from the maker, Wes Crawford. This may well be the perfect compact fighter, for me. The handle shape and dimensions are perfect for my hand. Because I can legally carry a handgun more places than I can legally carry a fixed-blade knife, and because many places have blade length limits, the Crawford Custom Kasper Scorpion may become my default favorite fighter. It is large enough to be a serious “primary” weapon on its own, but is small enough to be carried as a secondary weapon. I may well add another one or two of these this year. (When I really like a knife, I know to acquire one or two spares! Knife makers age, and a maker younger than me may get out of the business due to injury or other cause.)