A chart may say Water Two Bureau while its Life Palace contains Wu Qu, traditionally classified as Metal. A palace branch can have another elemental classification. These labels describe different things.
Name the object being classified
The bureau is derived from the Life Palace's stem-branch classification and serves calculation purposes, including main-star placement and the first decade's starting age. Wu Qu's element describes a star in traditional symbolism. A branch's element describes a position.
“Water bureau, Wu Qu in Life” is a coherent chart description. It does not make someone half Water and half Metal or provide a percentage of inner conflict.
Some traditions examine elemental relationships between stars and palaces. Such a reading must state exactly what it compares. Mixing the bureau, stars, branches and a Ba Zi day master into an unexplained score obscures the method.
Neither label alone establishes a missing element or an appropriate career. If a reading claims an elemental conflict, ask which two chart components it means.