Are relics like lucky charms or what?

Actually, the idea of relics are biblical!  One demonstration of the capacity a relic has to deliver the power of God's miracles, can be found in the book of 2 Kings.  In chapter 13 you can find the story of the bones of the prophet Elisha (the one who followed Elijah) bringing about a miracle.   When Elisha died, he was buried in a cave.  Some time later, another man died. He had to be quickly put into the same cave as Elisha in order to avoid a band of Moabite raiders who would pillage the land each year.  When his dead body "came in contact with the bones of Elisha, he came back to life and rose to his feet."  (vv 20-21).
     Something to keep in mind about relics is that any miraculous power they convey is not because of luck or magic or "mojo."  It is because God has chosen to manifest His power through them.  It's the same way God works miracles through the touch of a Saint long before the Saint dies.  It's also the same way God works through the Sacraments.  
     We demonstrate affection and honor to the relics just as we would demonstrate that same affection to the Saints themselves if they were present to us.  The relics are a remembrance to us of the holiness of that Saint's life.  They also provide us with a reminder that we too are called to be Saints.