The little wallet was called a multi-function purse by
Coach. I don't get dramatic results with wallets as I do with purses when I rehab. I think it is because the leather is thinner. I think you can wash and condition it just like a leather bag. Blackrocks will help disguise those scratch marks.
Unfortunately I don't think there is anything you can to remove the dye on your city bag. Too bad you didn't come here first. You can't dye over the top of black with normal leather dye. I might experiment with RIT dye remover. It might make it a gray color, which might be easier to dye over. The only other option would be to cover the entire thing with Leather Refinisher by Wood 'n' Stuff but it is an acrylic coating so it isn't quite as nice as leather.
You can wash and condition your husband's knapsack. It would help to see pictures and the creed, and to know if it has a lining, to know how to advise you. Several of us have been successful in fixing edges.
I've heard about the baby wipe trick. I would only recommend it for newer bags that can't be washed. I find leather cleaner to be pretty much a waste of money. Soapy water works better, or for bags that can't be dunked, I've used vinegar or a mild spray cleaner with success.