Quick answer
Some speech cuts and some heals, and the verse means both literally enough to matter. Words do something physical to people.
Read both lines
The first image is not exaggeration but description: everyone has been on the receiving end of a sentence that went in like a blade, and the phrase "there is one who" makes it a recognizable kind of person rather than a rare event. The second line's word is a healing word, the ordinary term for a remedy, so the contrast is between a weapon and medicine. What the verse establishes is that speech has an effect on a body and a life, which is different from the claim that words create reality. A wise tongue does not conjure health; it does what medicine does.
Related: Proverbs 12:25 · Proverbs 15:4 · Proverbs 16:24
New King James Version®, Copyright © 1982, Thomas Nelson. All rights reserved. Full copyright information. Scripture provided by API.Bible.
Go Deeper
If this verse has been used to put weight on you that it was never carrying, ask about it directly.