sharpener (n.)

late 14c., sharpenen, "intensify;" mid-15c., "make a point sharp or sharper," from sharp (adj.) + -en (1). Related: Sharpened; sharpening. The older verb was simply sharp (Middle English sharpen), from the adjective and partly from Old English gescirpan (West Saxon), scerpan (Anglian) "to score, scarify;" also compare scearpung "scarifying."

To sharpen (one's) pencil in the figurative sense of "prepare to get to work" is by 1957, American English.