Sorry Oofta, but I don't think your conclusions make sense, here. That dragon is going to be packing a LOT more force than a person would when they hit the wall, and that energy has to go somewhere...and if the wall is completely hard and immovable, like a wall of force, then all that energy is either going back into the dragon or being released as heat - probably a combination of the two. Contrary to your suggestion, the dragon would sustain far more damage than a person would from that impact. Conservation of energy, and all.
This also tracks common sense - we've all seen a bird hit a window at a fairly high speed and recover relatively quickly, I'm sure (sadly not every time, but often). But imagine what would happen to a person who hit a wall at 30 kmph.
Here's another example: ever been on a ferry? What happens when they hit the dock, even though at that point they are going as slow as possible? There is so much energy released that the ferry bounces back, and the dock has to be designed to do likewise or it would be quickly destroyed.
Now imagine that instead of the dock, the ferry is running into a 7mm steel edge, and doing so at full speed, and you start to see the implications of wall of force as an offensive weapon.