Welcome to you and Blue.
Since Blue has been nipping/biting on hands for almost a year, it may take more time to stop this behavior than it would if it had been stopped when he was still a tiny pup, but it is very doable with patient consistent training.
Here are a few things you can try and see which, or the combination of which, works best with Blue.
1. Any time Blue mouths/nips/bites at hands, that person turns their back on Blue and ignores him totally ...if they have been playing with him with a toy that toy is put away out of his reach. It is good to also teach "no nip" at the time his mouth closes on a hand. If he continues to pester that person, trying to nip his/her hand, he gets time out, this can be either in a gated off room or in a crate. If you do time out make it short...5 minutes. Message is...
you nip and all fun and attention is over.
2. You can spray your hands with bitter apple or some other bad tasting (non-toxic) substance that will make mouthing hands unpleasant. But do the "no nip" training along with this so that he learns that when you say "no nip" it means his mouth is not to be put on a human's hands.
3. Use substitutes: when Blue starts his hand nipping, say "no nip" and give him something he likes to chew on as a substitute. Praise him if/when he takes the acceptable item and lets go of the hand.
4. Always praise him if he stops the nipping on command...or even if he is just playing happily without nipping. Sometimes we focus so much on working on a negative behavior that we forget to let our dogs know when we are happy with their good behavior. They need that praise to know they are doing what is right.
Trini