Okay, so here's something I'm really curious about:
When a piece of armor has a certain amount of Defense bars for Normal, Piercing, Elemental or Shadow resistance, it's understood that that's just reflecting that one item, not your overall stats, so they're additive. Meaning if you have a helmet that gives 5 bars of Normal and 3 bars of Piercing, and an armor that gives 5 bars of Piercing and 4 bars of Elemental, your total defense is 5 Normal, 8 Piercing and 4 Elemental.