having studied both zen and aikido for over 20 years each ... I firmly believe that the highest achievement of an individual is to understand the essence of his/her own mind. when you have achieved that, then self-defense is irrelevant. having said that, unfortunately, there is little inherent in aikido that will get you to this point ... it's all depends on a teacher.
my suggestion ... find the enlightened teacher first and then study with him/her - whatever they teach. it's not at all what they teach that is important, rather that your decision to study is your price of admission to their insights ...
how do you find an enlightened teacher? how do know if that person is enlightened? how does one wolf know another? and if you are a wolf, why would you need another wolf to tell you that you are a wolf? and how do you study zen? is it like study a donut? does the donut define by the hole or there is really not a donut which is in my case, because i just ate the last one?