Basically I wanted dragons to be able to efficiently finish off armored opponents by chomping on one of their arm then batting them around and against hard surfaces until they're no more.
If you need a visual demonstration, here's one with a water monitor (live feeding) and one with Filthy Frank. Just replace the rat/hamster with a knight.
Now the problem with dragons isn't the square-cube law, but two semi-separate things:
Weight for material selection: when you start increasing the weight, the tendons, ligaments bones and wing flaps will be subjected to greater forces. This can be overcome with stronger materials (which are already present in nature).
Mass fraction of the wing muscles: Its mass is usually 25% of the TOTAL body mass, plus there are the wings. This means, the legs (fore and hind), tail and neck need every bit of trick to maximize the force they can exert for the least amount of weight.
That being said, how should the dragon's "Human Whiplash" work from a mechanical standpoint, given that we're going for maximum lethality, and how would their neck adapt to it?
The dragons in question are the six-limbed variants.