Switchblades are pretty much useless as fighting weapons because their lock mechanisms are so weak and, generally, the blades are of poor quality. A fixed blade knife is always preferable to any folding blade if you're in the unfortunate situation of having to defend yourself with an edged weapon.
I love knives, but don't carry one for self defense because TX law requires blade lengths under 4" for carry. And I'm no expert with a blade. A collapsible baton is probably the best non-firearm weapon you can carry, if your state allows it. Unfortunately, TX does not. Even with a CHL. They're verboten for carry.