Water is formless, but it has manifestations.

Ice, snow, frost, clouds... are all manifestations of water. The attributes often mentioned in cultivation are metaphysical, such as the ice attribute and the water attribute, which are two completely different attributes in many techniques and divine abilities.

Su He could manipulate water, but ice was much more difficult.

The water manifestation is an auxiliary divine ability, but it has a significant role, allowing the inheritor to manipulate the water manifestation at will.