[aristeides]

I understand that swans, in contrast, can kill people with the force of their wings.

[Salamander]

I can't see how. ( not that anything is impossible ) :)
The air pressure the wings generate actually work -against- the bird, as far as "blunt force trauma" goes.
The harder they "flop" you, the closer they come to lift-off, feathers and wings being what they are.
Once, while clipping one of the geese's wings, Bob (the gander) decided I was murdering her and threw his whole body upside my head. He then proceeded to "flop" me for all he was worth.
After the inital shock of having a 30 pound pillow hit me, I just turned around and yelled "what in h*ll do you think you're doing?!?"
When I -didn't- act cowed, he backed away, complaining bitterly.
That's the whole secret of fending off a "goose attack".
They're relying on *you* to panic at all the noise and movement they make.
Most animals will freak out and run away.
They can and do "pinch" but that's nothing compared to even a "friendly" horse-nip.....:)