While we are not yet a "carry what you want" state, like AZ or NH, from a PRACTICAL stand point, Texas is pretty good, especially now that we have a pre-emption law in effect. Any legal knife can be carried, either concealed or open carry, without the need for any permits or licenses.
A legal knife is defined as being single edged and a 5-1/2" blade as measured in a straight line, from tip to guard (or where a guard would logically be, if there is no defined guard).
The down side is that if it doesn't meet the criteria, one could be charged with carrying an illegal knife and thereby have a close encounter of the expensive kind with our Texas legal system. On the good side, again, MOST Texas LEOs don't really worry about knife law much. They are only going smack someone with an illegal knife charge as a "tack-on" charge if they have already have a reason to be looking at them because they were being an idiot or caught doing something else wrong. Texas LEOs don't walk around with tape measures in their pockets, but I've had several tell me that they use a dollar bill as a gauge. A dollar is longer than 5-1/2" and as long as the blade isn't longer than a dollar, no harm, no foul.
Hopefully, this next legislative session, the term "illegal knife", as well as the archaic ban on daggers, dirks, poniards and Bowies, will be removed from the Texas Penal code, and it will boil down to "what did the idiot actually do with the knife". Knife Rights almost got a bill through last session, but a last minute pissing contest over another bill resulted in the knife language bill being pulled from the Senate calendar.