The ship mounted four 4.7-inch Mk IX guns in single mounts, designated 'A', 'B', 'X', and 'Y' from front to rear. For anti-aircraft (AA) defence, "Hero" had two quadruple Mark I mounts for the 0.5 inch Vickers Mk III machine gun. She was fitted with two above-water quadruple torpedo tube mounts for 21-inch torpedoes. One depth charge rail and two throwers were fitted; 20 depth charges were originally carried, but this increased to 35 shortly after the war began. By mid-1940, this had increased to 44 depth charges.