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.
<a href="https://www.etymonline.com/word/sharpener">Etymology of sharpener by etymonline</a>
Harper, D. (n.d.). Etymology of sharpener. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/sharpener