Get yourself a grass whip. Here's a link to the one I bought. Grass whip. It's very light and you swing it at an arm's length, so little chance of injury (just make sure no one else is standing nearby!!). You can swing with vigor, or more gently - the blade is sharp enough to cut without lots of force behind it. I use it to try and keep the nettles and couch grass on the as-yet-uncultivated part of my plot under control.