干 (shield) and 戈 (halberd) were ancient Chinese weapons. Together they represent warfare. The idiom 化干戈为玉帛 means 'to turn swords into plowshares' (transform conflict into peace).
usage
Most commonly appears in the phrase 大动干戈, which can mean literally 'to wage war' or figuratively 'to make a big deal of something / go to great lengths.'
