I once heard of a “s’gula” for Shalom Bais for Shabbos: Sharpen your knives erev Shabbos by rubbing two knife blades against each another. I thought of a “s’vara” for this “s’gula”. Anyone want to venture an opinion?
If the knife is not sharp, you won’t be able to cut the challah properly, and that will cause frustration and anxiety (especially one is required to eat immediately after making the bracha, and here he won’t be able to cut the challah).