Lug

Lugs are small projections down the side of a shaft of a weapon or tool generally next to the eye of that implement. They are generally found in pairs and may extend up the shaft in some cases.

Lugs can help guide the head of the implement to sit straighter on its shaft assuming the head and lugs are straight themsleves.

These lugs are an oft forgotten part of reproduction medieval tools but are intrinsic to their form.