Why was clemency trending last week?
early 14c., from Old English arwan, earlier earh "arrow," possibly borrowed from Old Norse ör (genitive örvar), from Proto-Germanic *arkhwo (cf. Gothic arhwanza), from PIE root *arku- "bow and/or arrow," source of Latin arcus (see arc (n.)). The ground sense would be "the thing belonging to the bow," perhaps a superstitious avoidance of the actual name.
A rare word in Old English, where more common words for "arrow" were stræl (cognate with the word still common in Slavic, once prevalent in Germanic, too; meaning related to "flash, streak") and fla, flan, a North Germanic word, perhaps originally with the sense of "splinter." Stræl disappeared by 1200; fla lingered in Scottish until after 1500. Meaning "a mark like an arrow in cartography, etc." is from 1834.