Veteran wound treater here, my chickens and my own, oh, and when I was fifteen and nearly killed my sister. It's not rocket science.
1. Stop the bleeding.
2. clean the wound.
3. Antibiotic ointment
4. Keep it moist.
5.Oral antibiotic for all puncture wounds.
I like
@AngelaY 's suggestion of the tub of warm soapy water. What better way to cleanse a duck's wounds? Good fit.
The wounds need to be assessed as to type. Lacerations may need stitches. Tissues torn or lost will need daily cleaning and kept moist with ointment to encourage tissue growth and discourage bacteria.
If the wounds expose internal organs, that necessitates a decision to end the duck's suffering in view of likely fatal wounds.