One of the great bits about doing research or reading history is turning up little bits of unexpected information. I am currently reading John Julius Norwich's History of Venice. I have been promised a trip to Venice next year and so am reading up.
The word Arsenal comes from the Arabic words -- Dar Sina'a which means House of Construction.
The original Arsenal was started under the Doge Ordelafo when in approx 1100, he required all the shipbuilding in Venice to be nationalised. The centre of the operations were two marshy islands known as Zemelle. Over the next fifty years, it became a huge complex of dockyards, foundries, magazines, and workshops. Dante describes it in the Inferno. And it was called the Arsenal. Ultimately at its height, the Arsenal employed over 16,000 workers and was capable of turning out fully equipped warships every few hours.
I have no idea when the term came to be applied to a collection of weapons but thought it interesting.
The Doge Ordelafo is somewhat mysterious as his first name appears to be a virtual palindrome of the Venetian last name -- Falerdo. It is known that he was a member of the Falier family but the reason for his odd first name is lost in the mists of history.
More revisions but the Viking is getting better.