Sword of Damocles
Etymology
From an anecdote in Cicero’s "Tusculan Disputations": the courtier Damocles envied the luxury of the tyrant Dionysius II of Syracuse, so the king let him sit on the throne — beneath a sword hung by a single horsehair, to show the dread that shadows power. The phrase now names any threat that persists precisely amid apparent ease.
noun phrase · /SORD uhv DAM-uh-kleez/
A looming danger that hangs over someone even in a position of comfort or power.
What it names
The exact image for constant peril shadowing privilege — not a distant risk, but one suspended right overhead.
Example
The pending lawsuit hung like a sword of Damocles over every decision the board made that year.
Related idea
A sword of Damocles is a threat you can see hovering; a black swan is a catastrophe you never saw coming at all — visible dread versus total surprise.