I could see it being argued, very convincingly, that saints are capable of acquiring for us actual graces necessary to protect, guide, and help us, interpreting our petitions to help, guide, and protect us as us asking them to pray for us.
For example. **Monica is a Catholic **walking home from the library one night. Before she leaves, she asks St. Joseph to protect her on her walk. During the walk St. Joseph prays to Christ, asking Him to get Monica to take a certain path home, as her normal one has a mugger waiting for her. Christ grants this and Monica walks a different way. In a sense, St. Joseph protected her, but of course, as with all good things, it ultimately comes from the goodness of Christ. She didn’t ask St. Joseph to pray for her protection, but I think that’s implied in her request for protection, because what greater thing can a saint do for us than pray?
This is also just me thinking out loud. I don’t know if this is in accord with actual teachings.