Dragons should never grab you. They gain no meaningful benefit for it. They are better using their reach to fly around clawing and biting and strafing. They never want to be in close, because being in close provides no advantage, only liability.
Imagine if, in an alternate world, you had, say, Hit Points and Wound Points, and while normal attacks can wear out your HP (and make you tired), they can never kill you. The only way to deal WP damage would be to place an enemy 'in peril,' and doing that requires some sort of maneuver that shifts your fighting style.
You might have to grab someone to imperil them, or have them in a space where they cannot move because you've cornered them or immobilized them with a web or something. If you attack someone without any HP and they aren't in peril, your attack just does nothing at all, unless in a single hit you deal damage equal to their entire remaining WP, in which case you knock them out.
Did you ever play the video game Def Jam Vendetta: Fight for New York? It was a brawler game where you could use a variety of moves to wear someone down, but to finish them you had to use one of a small variety of harder-to-pull-off attacks. It ensured that the ends of a fight felt like the other guy was getting thoroughly beaten, not simply falling over because his bar of health ran out.