OK, so when you see either of them starting to get the "look" immediately intervene. This is what I do:
Brutus will get his look on and I will immediately in a loud voice say "Brutus knock it off" if he immediately does not come out of it, I will tell him "No Brutus" and put him in his kennel and tell him he can come out when he behaves. I ususally give him abut 5-10 mins of time out so he can calm down and he understands that his behaviour is not acceptable. He gets it. He will come out normal and crisis over. The key is to catch it before it escalates into a fight, because once they are in that fight zone, no words will help. If they do get into it, never pull them apart near their head or face area. I grab one of the dogs by their hind legs and pull them backwards to separate them. This avoids the chance of me getting bit. Ever since we put Brutus on Prozac, the conflicts are almost nil and I can redirect him much much easier. Maybe you can talk to your vet and see if this is something he recommends. In my opinion, Willow is reacting to Walter. Frankie is the most passive dog in existence and he will eventually have enough of Brutus' crap and react. Good luck, as you know the key to getting him to understand the behaviour you will accept is consistency. make sure everyone in the house uses the same command when redirecting Walter out of his mood.