to prepare horses and chariots for battle
廞 centers on preparing or arranging military equipment, specifically horses and chariots, for battle. Its meaning is narrow and archaic, tied to a specific historical context.
廞 combines 广 (building or shelter) with 欽, which likely contributes the sound. The character is rare and its exact historical development is uncertain, but it is associated with preparing military equipment in a sheltered area.
Under a shelter 广, the complex shape 欽 looks like a person 欠 beside metal 金, suggesting someone working with metal fittings to prepare horses and chariots for battle.
For キン, imagine a king (キン) inspecting the prepared chariots under the shelter: king -> キン, and the king oversees the battle preparations.