I don't have a lot of experience with ducks yet, but I do have experience with raising other animals, and if I was worried that a baby seemed weak and might not make it, I think I would keep it close to my body for warmth and comfort, and talk lovingly to it, and encourage it, and give it some...
I just recently hatched a runner and kept him in the incubator for about 18 hours before I put him in the brooder with his siblings. Once in the brooder, he was still wobbly until the next day but quickly caught up, especially after eating and drinking a bit.
I also recommend putting something...