This is a silver hammer - called a Uchide no Kozuchi. This lucky hammer is mentioned in ancient Japan Tales Mukashi Banashi (昔話). One of the most popular - a Issunbōshi (一寸法師), is a story of the boy's growth into one sun. In ancient tales boy named Issunbōshi protects the princess, the daughter of one of the richest feudal lords, from the demon who attacked them while walking to the temple of the goddess Kannon (観音). Issunbōshi acquired magical hammer Uchide no Kozuchi. The Princess waved a hammer three times, - Issunbōshi grew up and became a man and a proper protector. It has an interesting background and story. This piece is missing the original glass housing - but it has a 10 year anniversary plaque attached to it. This item is marked in Japanese on the base of the hammer near the handle.
The base measures approximately 7.5 inches long and about 5 inches wide. The Anniversary description may be removed by the new owner.