The best replacement for sharpener is stone.

The best alternatives to sharpener are rated as following:
★★★★★  stone
★★★★  leveler
★★★  spyderco
★★★  whetstone
★★  diamond
★★  grizzly sharpener
★★  sharpener
★  sharpening stone
★  nik sharpener pro
★  photokit
★  topaz detail
  chefs choice model 120

Your alternative for sharpener is not listed? Suggest!
Speaking about sharpener, one probably shouldn't forget about eraser.

Other search terms related to sharpener and their ratings are:
★★★★★ eraser
★★ bonus serrated knife sharpener
★ leather sheath
pencil
You have in mind a companion for sharpener and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of sharpener in all years. Click on graph for more.
sharpener
stone
leveler