A strong and extensive background in bare hand combatives is what most edged weapons trainers of any repute will require first. Some will say it's just them making a buck but the essentials are still necessary.
"Hanging around the gun store" is in and of itself not a qualification one would be advised to point out. Some practical/actual military/leo training would be far superior and credible should credentials be needed.
A karambit is just a knife - there are others that can be used and which are equally recommended by others for "git off me" work. Those are generally purposed blades not used for any other tasks. That leads to what blade you already EDC and why would it not be considered as it's already on you?
Lots of folks don't carry specialty blades of a self defense nature simply because their primary blade can do that job and they will be much more familiar with it as it gets used and reinforced dozens of times a day. Special blade, special carry, special motions vs normal low profile blade, used normally all day, normal familiar motions. We really only have so much time to dedicate to training and it adds up - an EDC will have triple the use vs an hour a week with a "combat" blade.
A Sharpy in the top front pocket and a lock blade in your jeans pocket, you might already be well covered day to day. Impact weapon, edged weapon. Either will be useless without bare hand defense techniques well practiced and a mind toward not being attacked in the first place.
Lots of folks ask what is the best HD weapon and never ask how they could secure the home better in the first place. In Europe they put up defensive fencing up to an including barbed wire, in America you walk across the lawn and break the window in the door, IN!
Same with our personal security. We ask what exotic tool we should use but have no idea what to do if two guys walk up and cross the street to confront us. Goes to why did you get into the situation in the first place? Wrong place wrong time.
Less about what knife, more about how to avoid it and then how you could handle yourself no weapons at all.
#walkaway from the gun counter was a good move. Keep walking.