the Flail was originally a farming tool but serious evidence for its use as a battlefield weapon is... sparse. I think the best example is probably the Bill, which was originally a farming tool and was adapted to use as an infantry pole-arm. Most farming tools had to undergo serious modification before they became effective on the battlefields of medieval Europe, and in general the trend of massed infantry weapons is that they make up for their own and their user's shortcomings through their effectiveness in mass formation and/or ease of use.

Outside the battlefield, there's the Messer, which is not dissimilar to a machete, which was used by city-dwelling civilians. It was cheaper and easier to make than a true "sword" because the was it's handle was put together meant it could get around certain Guild laws regarding the construction of sword hilts, reducing the cost.