This is a Negau helm.
The Negau helms were priestly war helmets made in 450-350 BCE. Etruscan runes were etched into the metal sometime after their creation and before their ceremonial burial in 50 BCE. One of the helmets has Germanic writing, the earliest Germanic text ever found.
Which reads "Harigast the priest." HARIKASTI is the name Harigast and TEIVA is the title of priest (from the word for "god"). and The <k> in Etruscan could indicate a k or a g and the <v> can stand for v or w. This is fascinating confirmation of Proto-Germanic reconstructions. We had reconstructed the word for "god" as *tīwaz , a word dated to around 500 BCE. You may recognize the word as the first element in the word Tuesday. The discovery of TEIVA on the helmet (read as teiwa) brings us ever so closer to the original form. Harigast's name means "army-guest."