You can try time out. I have an aggresive muscovy drake [actually mine is a seriously distrubed drake -- he was a rescue and I suspect his early life has left a deep mark on his psyche.] I keep a dogcrate in the garden, and when he comes along trying to bite my feet and legs, I pick him up and plonk him in the dog crate. It only takes 3 minutes for him to come out chastened!! I recommend this as first line of action for behavior change modification in aggressive drakes.
I have realized recently, that all I need to do is pick up my aggressive drake and talk to him -- he doensn't fight me once he has realised he can't get away. I am able to talk to him quietly and stroke his head, neck and carruncles. That boy loves having his carruncles stroked!!! When I put him down, he behaves the way he does when I let him out of the dog crate. He does lots of flapping his wings, fluffing his feathers and dipping his chest to the ground, but goes off and doesn't try and bite me again. Maybe my boy really wants cuddling and doesn't know how to ask nicely!!!