磨刀

to hone (a knife)

to rub / to grind / to polish / to sharpen / to wear down / to die out / to waste time / to pester / to insist

grindstone / to grind / to turn round

knife / blade / single-edged sword / cutlass / CL:把[ba3] / (slang) dollar (loanword) / classifier for sets of one hundred sheets (of paper) / classifier for knife cuts or stabs

whetstone (for honing knives)

lit. to sharpen one's sword (idiom) / fig. to prepare to attack / to be getting ready for battle

whetstone (for honing knives)

lit. sharpening the axe won't make the wood-splitting take longer (idiom) / fig. time invested in preparations is not lost / a beard well lathered is half shaved