The last chapter 2 accessory (2-4?) is excellent for defense. Along with some good armor, you can have fine SR tanks. Naoe (10% regen) works really well for me despite having no defense raising abilities. I can get her to 2800 defense at level 35, which isn't too bad. The problem is mostly damage, especially when you need to wipe aoe enemies before they kill you.

Thanks for the slingshot description.