I would not consider carrying a knife for defense without greatly improving my knowledge base
I agree partially.
I know of too many cases where the simple use or even presence of a knife and the will to use it was effective in self defense. Knowledge is always valuable, especially in knowing what is and isn't legal to carry and use, AND I'm a devoted advocate of training to develop skill to go with the will to defend yourself, but people can and have defended themselves effectively when the attacker expected them to be helpless.
OTOH, where the attacker is more determined, and I've found no way to block determined attackers from anyone's Outlook schedule, greater skill would be called for.