E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
So called from Pistoja, in Tuscany, where they were invented in 1545. (Latin, pistorium.)
To discharge ones pistol in the air. To fight a man of straw; to fight harmlessly in order to make up a foolish quarrel.
Dr. Réyille has discharged his pistol in the air [that is, he pretends to fight against me, but discharges his shot against objections which I never made].W. E. Gladstone: Nineteenth Century, November, 1885.