Never buy a defensive carry knife that doesn't have an available trainer in the same exact profile. 🗡️
Discussion
Defensive knife sounds like a terrible idea. Because to use it and it not be murder, the other guy has to be threatening you with at least another knife. And rule #1 of knife fighting - Nobody wins a knife fight. Two people in a knife fight both get torn to ribbons.
A "get off me" knife is useful in last ditch circumstances, and they are unobtrusive, vanishing on the beltline. Good for disabling dogs, if it comes to past, too.
The situation where I would use one of these has already put me past worrying about charges, if you know what I mean.
Consult an AI to learn about your state's laws. In Texas it is generally permissible to use a defensive knife to save your own life.
A knife is just a handy tool for all kinds of situations and general use.
For defense they also have pretty powerful pistols the size of a wallet. (I'm thinking of the 7 shot .380s made by almost every brand now.) If you're in Texas I think that's just as legal as the knife.