Central to the Special Air Service badge is a dagger, surmounted by wings.

It was inspired by SAS founder Colonel David Stirling, who asked a Cairo tailor to make such a badge on which he envisaged was a symbolic sword of Damocles.

Australian World War II commando companies used a Sykes-Fairbairn fighting knife on their badges, adding postwar a boomerang.

The knife was designed by William Ewart Fairbairn and Eric Anthony Sykes, two prewar British colonial police inspectors with the Shanghai Municipal Police in Shanghai, China.

Sykes and Fairbairn were responsible for policing Shanghai’s triad gangs, where a dagger was the weapon of choice.

Based...