FWIW i recently taught a knife defense class. I started the class by stating the following.
Rule 1 RUN!!! This is only if put in a life or death situation you cannot get away from.
Rule 2. You WILL get cut. These techniques "might" allow you to control where.
I gave no delusions of grandeur that anything taught would protect them from the blade. Just possibly increase the chance of survival.
As far as handing over the wallet, I have always been taught not to just hand it to the person. To throw it away from them. If they go for the wallet, run. If they do not, they probably were not solely interested in it anyway, time for plan B. Thoughts?
Learn more ways to preserve rather than destroy. Avoid rather than check. Check rather than hurt. Hurt rather than maim. Maim rather than kill. For all life is precious nor can any be replaced.