Don't know if the thread is still viewed, but I'm new to the forum and this is a sweet spot subject for me!
Knives used for self defense are not magical tools that will save your bacon from a life threatening encounter. If you don't train to use it, or any type of self defense training, it won't make up the difference.
Knowing your capabilities determines your knife shopping. If you have a boxing skill, you can ease into training with a karambit and be successful with the reverse grip by throwing "punches".
Cold Steel knives are far and away the best value in tactical blades, with a great deal of diversity. Anytime you see these exotic steels in a tac knife, you should only consider it for collect-ability, because once you get passed an AUS8 steel and above $200 you're seriously over paying for what you need.
For the OP, I'd recommend a Cold Steel GI Tanto. It's a 7 inch blade, comes in a Kydex sheath, retails for about $25 and is damn near indestructible. Look here: https://youtu.be/6qV0zaN83zM .....this guy tortures bush/tactical knives to see if the manufacturer's claims hold water. NOTE: took him over 8 episodes to actually destroy the thing! Also, they've upgraded the sheath over what is shown and went to scales over wrap.