Nothing chaps my ass like having to travel to “non-permissive environments,” particularly in reference to entire states or cities. Court buildings and other federal locations are typically restricted and this is unlikely to change. The states and cities that prohibit the carry of defensive firearms are obviously populated with people who like having their betters, because in all such places the elites can get carry permits, or have armed security, but the peasants are left helpless. Of course, the peasants keep voting for these elites. I would hardly care, except that I sometimes must travel to such cesspools. Anyway….
When you must set foot in such urban cesspools you likely can’t carry your handgun (you also probably need to avoid stepping on needles and human feces, but that is another discussion) so what are your alternatives for carry? Well, I deal with non-permissive environments by carrying the tools I always carry, minus the gun and reload. In truly restricted environments I may need to change from the usual folding knife to a tiny keychain multi tool so that I at least have a cutting tool on me (for myself, cutting tools are for emergency tasks, not likely for defensive use). Relying on my daily tools makes for a pretty easy transition as I can rely on the things that I am already familiar with.
In particular, I maintain OC Spray and my flashlight even in restricted environments. I always carry these two tools along with my gun anyway, so if I need to go into a state/city that prohibits firearms, I keep these two options, along with my medical trauma gear that I also always carry. I am not going to pretend that this is ok and that these tools are an adequate substitute for a handgun, they are not, but unfortunately in such places you are not a citizen, you are a subject, and you must play the hand you are dealt. The benefit of keeping tools that you always carry anyway (and I firmly believe a handheld light and OC Spray should always be carried when carrying your handgun) is that the body location of, and deployment of, these implements are ingrained already as you should routinely practice with these tools.
In truly restricted locations or when traveling overseas the flashlight will usually be good to go but the OC Spray might be prohibited. Under such circumstances I usually carry the light, which is always on my support side, and will carry a tactical pen on my dominant side. There are benefits to having a tool available to each hand. Both can be used for impact and the light is, of course, an excellent defensive tool in low light.
Therefore, I am a fan of simply offloading the lethal tools when needed and carrying the less lethal defensive tools that you already carry when entering restricted environments. I am not a fan of dedicating a lot of training time to tools that are needed seldomly as a substitute; rather, just rely on the less lethal tools you carry on a daily basis, which you should be doing.
Concerning knives, I find that most restricted areas that prohibit firearms are usually very restrictive of edged weapons, particularly fixed blades, so in the rare circumstance that a blade can be carried but a gun can’t, certainly carry a blade. However, the flashlight/OC Spray combination can go almost everywhere in the United States, and the Flashlight/Pen combination can go most places elsewhere as flashlights and pens are useful tools to carry, obviously, beyond self-defense.
That is my approach to dealing with restricted environments. Having some tools is certainly better than having no tools at all. Perhaps one day all Americans will stop voting for those who keep them disarmed and helpless, but until then….