Now granted, this is a hybrid Pekin (so a meatie), and is much larger than most ducks.
Here's how you hold them if you can grasp both legs easily and they're calmer
If they're not calm, your hand is too small, or you can't support their weight, this is how we were taught to hold, so that they...
That's how I held my pekins too when I showed in 4H. Some people held them tucked under one arm and brought the body against their chest so their free arm could take some weight.
If I can catch one of my pekins, I'll get some pictures to show how I've seen my friends hold them for show