The actual story of Damoclēs and his monarch Dionysius is of no relevance here, 

except, that is, for the punch line, 

which left Damoclēs sitting at dinner beneath a naked sword suspended from the ceiling by a single thread.

 The moral of the legend being that a person’s situation in life is always chancy. 

Another moral might have been that 

if you find yourself at dinner with a sword hanging over your head, move seats