A real waste of my time has been the hours I’ve spent looking at “fighting” knives - they look more like over-priced CAMP knives. Here are some ideas for a pair of REAL fighters, gathered from elements from several designs. FIRST, a fighter should offer you maximum REACH, along with maximum HAND PROTECTION, so here we go. My “MARK I” would combine a 15" Mainz gladius blade - with a double-tanto 5" POINT, and meeting the guard at 2 1/2" - to - 3 1/2" wide. Two grip shapes I find attractive are the Swiss-German baselard “degen” and the “Holbein”. The baselard is straight and round with a slight palm-swell. Its successor - the Holbein - is flatter, with pronounced hand-swells - it resembles a flattened hourglass or Coke bottle. The cross-guard would be a 6" WIDE, quillon-shape (HONSHU “Crusader” and “Arming Dagger”), combined with a hand/finger guard such as the “musketeer” main guache provides, The “MARK II” would have the SAME features, but with a triangular, hollow- ground blade, meeting the guard at 1" - to - 1 1/2"
I have a Marine K-Bar and EK Commando my father carried in Vietnam, a Randall from my uncle from same, and a Blackmoor dirk I picked up somewhere or other. For what you’re describing I imagine an Arkansas Toothpick or Bowie knife would fit the bill.
Fighting, folding, “tactical” knife prices are insane, so I’m glad I kept my hand-me-downs.
As a kobudo / kenjutsu practitioner I own many iato / nihonto katana. Y’all think guns keep you poor, wait until you’ve purchased a custom sword from Japan “what was that price again, because I swear that’s what my last car cost me?!” 
If anyone has anything approaching these, you can bet they’re custom-made - the last price I saw on handmade, custom Japanese swords was $5,000.00 minimum - they’re probably in the $8K - to $10K range by now - all that folding and hammering, you see. I just let my imagination take off on what I’d want if I won a PCH sweeps. KURT
I did medieval reenactment combat for almost two decades, and while I was focused on longsword and poleaxe, I did spend some time knife fighting and studying other hand to hand and smaller blades.
Your fighting knife will definitely depend on your fighting style.
What you seem to be looking for would be a custom piece, so try looking on bladesmithing forums and find a forge to custom build it for you.
Expect it to be $$$$$$$$
I figured as much - and after I win a PCH sweeps! Just shopping for a maker would be a pain, up-and-down.
Who do you plan on fighting?
I’m a big Active Self Protection Fan. Very very few knife defense videos, and those people did not have a gun.
Not necessarily bad, but I don’t carry a knife often unless I need it as a tool. I have some defensive knives, but they make carry more uncomfortable. One day I’d like to get a WPS fox folder. They look like good as defensive and utility knives, but even then I don’t always have room for my pockets with a knife, even though I should just have one as a tool.
I always carry a knife as a tool at least, mainly because I was first on scene of a nasty rollover accident (dude passed out and clipped a light pole at about 60, tore the car in half) and the driver was pinned in his car by his seatbelt…. Had the car caught fire, (it was smoking) all I could’ve done was watch him burn to death.
On the SD side of a knife, I’m comfortable enough in my hand to hand skills that if I don’t have a gun, my folder will suffice.
All you need is about 3” of well placed blade to be almost immediately lethal. Also, even if not lethal, slashed arms and stab wounds are definitely distracting to an attacker! 
I have a few folding and one spring loaded knife i always have one on me tool or protection which ever needed
I always carry a Benchmade Griptilian my son gave me 
It’s a great work horse, but if it comes down to it being my self defense, then I’m probably way past screwed.
I’ve carried a knife since I was 14 years old. That’s when I first started working in the Meat department at the local grocery store. I always have a knife on me. I spent 51 years working in the Meat Department. A knife just seems natural to me. I learned to respect my knives. I do have a collection of knives, mostly wood handle butchers knives. But also folders and spring assisted, fixed blades and hunting knives. I have a passion for knives.
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I can’t remember when I didn’t carry a pocket knife. My Uncle gave me a two blade Barlow I was super proud of for years, but every one after was a lock blade.
I’m willing to bet it’s razor sharp! And gets touched up daily if you have to use it!
Leroy Jethro Gibbs - NCIS - Rule #9: Never go anywhere without a knife.
I carry one in my pocket ALL THE TIME. I lave four in my laptop bag. At my workstation I have three more within arm’s reach. In the truck, I have three within reach of the driver’s seat and an 18-inch roofing ax. I can’t count how many knives I have laying around at home. I also have a collection of GI bayonets and replicas. One I am particularly proud of is an 18-inch Wilkinson bayonet from 1906 which fits a Lee Endfield No.1 Mk1.
Does anyone know where I can get a government forgiven loan? There’s a few new knives that I’d like to buy?