IDIOMS: A DOUBLE-EDGED SWORD

Something referred to as a ‘double-edged sword’ has both good and bad consequences, although the idiom tends to warn that serious negative consequences are being concealed. For instance, “Freedom of speech is a double-edged sword.” The metaphor may have originated from an Arabic expression that was first referred to in English in the 15th century. This is because a literal double-edged sword, one that is sharp on both sides of the blade, was typical among English-speaking cultures while many early Eastern swords, like the Arabic saif and scimitar, are traditionally curved and edged on one side.
The Roman general and statesman Julius Caesar, born in 100 BC, warned that: “Patriotism is indeed a double-edged sword. It both emboldens the blood, just as it narrows the mind.” Similarly, the Bible contains passages claiming that “the word of God is living and active, sharper than any twoedged sword, piercing to the division of soul and of spirit.”