Part of the fool run. The second half repeats verse 7 word for word.
Quick answer
Same conclusion as verse 7, sharper picture. A drunk man with a thorn in his hand is holding something that will hurt somebody, and he does not know it.
Read both lines
The repeated second line makes the comparison the only variable, so the two images are meant to be read together. Verse 7 said a proverb in a fool's mouth is inert. This one says it is dangerous. Both are true and they are not in tension: the saying does no good and it can still do harm, because the fool waving it is not tracking where it lands.
The drunkard detail carries the weight. He is not malicious, he is impaired, and impaired handling of a sharp thing is how people get hurt without anyone intending it. Anyone who has had a true verse quoted at them by someone who did not understand their situation knows precisely what this describes.
Related: Proverbs 26:7 · Proverbs 25:20 · Proverbs 18:21
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.