That's it? Common and Magic? What about god damn Legnendary or whatever the yellow items are called? You know, about the only things in the game actually worth bothering with besides selling for gold. Talk about a completely worthless skill, this is it.
You can override TreasureTable.txt in \Data\Public\Main\Stats\Generated\ with your own table. You have to extract that file from Main.pak first. I have my own table that improves the skill somewhat. My table gives Lucky Charm 6 a tiny, tiny chance to find Legendary items, in addition to adjustments for every other skill level. But you can't play multiplayer with a modified treasure table.