It is a very interesting discussion, but ...
You know, there is no way to keep weapon with you all the time. Your skill is useless against hidden dangers. Even your proper posture and movements will not help because mostly, it is no time for it.
I would like to suggest that proper posture and movements are a good way of researching how to deal with hidden dangers!
To me, proper posture includes being relaxed, which means upright, and yet with a focus in my tanden - so some element of tension within the relaxation. In such circumstances I am better able to react.
If instead I am not relaxed then my movement is less good, and I tend to react slower.
I find this proper posture increased by weapons practice.
As I heard from one teacher - you need to have a sword in your mind!