sword of Damocles

Examples from literature

Japanese swords are famous because they are very sharp and strong. 
Samurai warriors used swords. 
So, sword makers stopped making swords and started making knives. 
They made the best swords in the world. 
They used metal to make knives and swords, and moving parts to build war machines, like catapults. 

sword | American Dictionary

sword
noun[ C ]
us/sɔrd, soʊrd/
a weapon with a long, sharp, metal blade and a handle, used esp. in the past