As iron sharpens iron,
so one man sharpens another.A quick study of how iron us used to sharpen Iron during the period the proverb was written revealed the iron that was used to sharpen an iron tool is much the same as the common sharpening rod we find today in a cutlery set.
These rods were used to maintain the edge of a tool like a plow or sickle or and ax as well as maintain the edge on a weapon like a sword.
The rod when used properly kept the edge straight because of use the edge would start to lean with use. The rod would help straight up the edge to keep the tool's from leaning more and eventually breaking off leaving the tool dull. The rod when used frequently and properly would not remove much metal. This is not the case with modern grinding sharpening where the edge is filed or ground to get it sharp.
In the time of the period the rod was used to keep the tool or the weapon functional and looking good (Also, look at Eze 21:9).
A paraphrase of the verse could be.
As the rod maintains the tool,
so one man make another to look good.
