I'd recommend buffing Long Arm to last 4-5 seconds instead of three. Without Burden of guilt, this talent isn't as effective. Pursuit of Justice should also stack on top of any normal speed boost you have (Like the Pandaren Step enchant)
Make Hand of protection so it can only be put on an allies, not self cast. In return, allow us to cast Divine Protection in a fear/stun/disarm (like from a shadow priest) and/or allow devotion aura to be included on Unbreakable Spirit/Clemency.
A damage buff isn't a huge concern, but buff our damage to 22-25% instead of 30.
With those two changes, I think Ret will no longer be consider "squishy" and a first target, also, with the devotion aura buff, you'll bring more utility to your team.