The rope connects, and wraps around Toothless's mouth, but isn't much of a deterrent. The dragon hadn't planned on biting Roland or setting him aflame in the first place. Just ramming into him as fast as possible.

Meanwhile, Hiccup lights Inferno. Aiming upward, he throws the flaming sword into the air, his metallokinesis guiding it upward and onward with tremendous force, and stabs it right into the Faceless's beating heart.