Steve
Mostly Harmless
I think that what is not universal is pretty much everything you think is universal.Self-defense always depends on the person. A person can't defend themselves outside of what they are capable of doing. The only things that are really universal are the non-martial arts, non-physical aspects of self defense such as, don't walk alone at night, always park in a well lit area, always be aware of your surroundings and other things like that are going to be universal. A person's health is going to limit how much can be learned and what can be deployed. Someone that isn't flexible will have trouble with doing TKD type kicks to the head. A person with one arm may not be able to do BJJ as a self defense option.