U

cross swords

noun

a weapon having various forms but consisting typically of a long, straight or slightly curved blade, sharp-edged on one or both sides, with one end pointed and the other fixed in a hilt or handle.
this weapon as the symbol of military power, punitive justice, authority, etc.: The pen is mightier than the sword.
a cause of death or destruction.
war, combat, slaughter, or violence, especially military force or aggression: to perish by the sword.
(initial capital letter) Military. the code name for one of the five D-Day invasion beaches on France’s Normandy coast, assaulted by British forces.

Idioms

at swords’ points, mutually antagonistic or hostile; opposed: Father and son are constantly at swords’ point.
cross swords,
1. to engage in combat; fight.
2. to disagree violently; argue: The board members crossed swords in the selection of a president.
put to the sword, to slay; execute: The entire population of the town was put to the sword.

noun

a thrusting, striking, or cutting weapon with a long blade having one or two cutting edges, a hilt, and usually a crosspiece or guard
such a weapon worn on ceremonial occasions as a symbol of authority
something resembling a sword, such as the snout of a swordfish
cross swords to argue or fight
the sword
1. violence or power, esp military power
2. death; destructionto put to the sword

Old English sweord, from Proto-Germanic *swerdan (cf. Old Saxon, Old Frisian swerd, Old Norse sverð, Swedish svärd, Middle Dutch swaert, Dutch zwaard, Old High German swert, German Schwert), related to Old High German sweran “to hurt,” from *swertha-, literally “the cutting weapon,” from PIE root *swer- (3) “to cut, pierce.” Contrast with plowshare is from the Old Testament (e.g. Isaiah ii:4, Micah iv:3). Phrase put (originally do) to the sword “kill, slaughter” is recorded from mid-14c.

Fight, either verbally or physically. For example, At every policy meeting the two vice-presidents crossed swords. This phrase alludes to the ancient form of combat using swords. Also see at sword’s point.

In addition to the idiom beginning with sword

sword of Damocles

also see:

at sword’s point
cross swords