Last week, the U.S. Army announced that it had finalized a $21.9 billion deal to have Microsoft (NASDAQ:MSFT) provide 120,000 augmented-reality (AR) headsets for its troops over the next 10 years. Investors have responded enthusiastically, bidding Microsoft stock up by more than 7% since the announcement. But what will this deal really mean for Microsoft? Image source: Getty Images. The deal The contract is worth upwards of $21.9 billion and could...