What is The Harpoon Gun

The Harpoon Gun is the weapon used to accidentally kill Dewey Denouement. At the beginning of the novel, Carmelita Spats asks for the gun to shoot crows (which may be carrying the sugarbowl) out of the sky. Count Olaf later uses the gun to threatened Dewey into telling him the code for unlocking the Vernacularly Fastening Door, which is how he is accidentally killed.