Water nurtures us, it is flowing and can support us, or drown us in excess, it chooses the path of least resistence, and can swamp us into immobility. Its volume can be as gentle as the rain-drop, or as violent as the Tsunami.
Defence is critical in fencing. Proper control of defence will make the fencer impenetrable, and allow a fencer to generate attacks of their own.
As a fencer, gaining the aspect of Water in our defence allows us to nurture attacks, supports our stance, drown our opponent's attacks in a flurry of defence, and do so with the most flowing ease, or with irresistability.