Yes, the bleeding would have helped clean it out, so long as it wasn't too excessive.
Keep the foot clean, perhaps allow the duck to swim in some warm water with epsom salts added, making sure he doesn't drink it.
We have a product here in Canada called Silver Honey, from Absorbine. Can't read where it's made (honestly, white on yellow type?!?) but it works wonders. I think you can also use an antibiotic salve like Neosporin, and wrap up the foot if possible.
I'd give him at least a week for it to scab over and heal enough before he's allowed more movement.