Been there done that. If you patch the surface by either sewing or patching, you could be interfering with the planned "tear and react(the Kevlar)" of the design of your chaps. Tried sewing them once with 40# fishing line and the saw snagged the heavy line and tore deeper into the chaps. Same damn spot each and every time. Can't tell you how many pairs of sweat pants I've cut over the years. Buy another set of chaps. Keep the damaged ones as extras for emergencies. Someone who sews saddles, seat covers, backpacks and such can repair yours so it won't be too far from the original designed planned failure of the chaps when cut. Be safe.