Thank you for the comments.
Conrad the point about a dominating gaze is very important. But I think there is a difference. The practiced gaze of a yakuza might be physically frightening. You can compare it to the fierce nio statues
at the entrance to temples. But the gaze of a master of martial arts is not just intimidating. It looks into your soul and lays it bare and ice cold.
Tom I take it to mean looking at the leaves. But there can be layers of meaning. Old or new. Intended or unintended.
I don't think the original phrase is linked to a particular ryuha.
In my last blog post I gave a link to a cool nature column
in the Daily Yomiuri that explains the science of the colours of autumn leaves.