Sharpened is a verb. It describes the action of making something sharp.
sharpened
part of speech
The part of speech for this particular word is a noun.
The part of speech for "answer" is a noun.
adverb
what part of speech is beneath
Your canine teeth can be sharpened by going to your dentist, where he/she will probably add a contour in place, but if you mean 'sharpened' like a pencil sharpened, then talk to your dentist about that.
to sharpen, sharpened, sharpened. sharp = an adjective.
The part of speech for "explicit" is an adjective.
The part of speech for "twirl" is a verb.
The part of speech for "unfamiliar" is an adjective.
The part of speech of "came" is a verb.