I've grown to love the Defender, but he's spot on about how weak it is. The only safe way to play it in PvP is to use it as a choke point with Saint-14 equipped, and run Armor of Light. That both forces you to stay inside the bubble and makes you a huge purple target. You can always try a No Backup Plans build if you want to run around with an overshield and tank shotgun blasts, but who does that?