Translation
If the iron is dull and he does not sharpen
Go to footnote numberthe edge,
Go to footnote numberhe must be stronger to prevail,
Go to footnote numberbut wisdom brings the advantage of success.
Paraphrase
If the iron ax head is dull and if the one working with it does not sharpen it, the work will require more strength to get the job done, but if he is smart, he can get the job done faster and thus look stronger. The one who has the wisdom and knowledge to use the tools available to him looks stronger than the one who tries to use brute force alone.
Footnotes
1: “sharpen”
This verb means “to be slight or be swift.” In this case it is the idea of “swift” that is sought after. When one sharpens a tool with a stone (or a file) he moves it “swiftly” back and forth.
2: “the edge”
Literally, “the face”. “Surface” is another option, and notice that the word “surface” has the word “face” in it.
3: “stronger to prevail”
Here Solomon has used two different words for “strength” back-to-back.