Yes, but as your working with the bitter end there's no significance to the loss of strength in that part of it.

You do want to have a proper amount of cable free after the last point of contact with the device it's operating, and with heat it's A Good Idea to have a heat sink between that point and the cable end you're about to twist-weld. Pliers works for most folks, or a Vise-Grip if you think losing your grip on a pair of pliers could happen.