You might clip a couple of inches, in case it's a tuck selvedge.

It does take some power, so possibly you just did not put enough strength into it. Some kiltmakers say they don't usually rip 16-ounce fabric, so scissors are allowable.

However ripping usually will produce a straighter, cleaner edge. You'll still have gently to pick out a couple of threads from each side, but probably fewer than with a cut.