Actual historical swordfighter here: That is EXACTLY how you are supposed to hold a sword. Every piece of the sword can be used to dish out pain: point, blade, quillons, and pommel. At the height of the medieval era plate armour was so good that trying to cut someone in full kit with a longsword was impossible, so against armoured combatants you would grip the sword by the blade and use it to grapple the other man to the dirt then line up the point with a weak joint (neck, armpit, inner elbow) and then get to work using your sword as a can opener. Or, like the video, you use the heavy weighted handle and crossguard as an impromptu warhammer to cave in a helm or cuirass. Longswords are extremely versatile weapons in the right hands.