SIMPLE BUT EFFECTIVE
A female friend of mine recently used a wrist lock technique I taught her several years ago to drop a man who was bothering her. She was also carrying at the time, but she chose not to use the threat of a gun to handle the situation. Although the guy was much stronger and larger than she was, the one-handed technique brought him to his knees instantly. (She said the look on his face was priceless!)
The most significant part of the story, from my perspective, is that she had not used the technique in all the years between when I taught it to her and this instance. Simplicity and effectiveness are the keys for most people who want to include martial art skills in their bag of tricks.