Bringing back a deterrent spell is a good idea, every season since the end of Wrath has been Train down the Ret.
Retribution Aura: 1min cd.
Unleash the wrath of heavens upon your enemy target, sharing 30% of all damage taken with him/her as Divine damage for the next 6 seconds.
Damage dealt cannot exceed the Paladin's total health.
I also think that we lost all of our perks so that Holy could get them, to do some justice to that act of disrespect the talents have to be more powerful for their true spec!.
Repentance has to be instant cast and physical for Ret, cooldown doubled (30 sec)
Burden of Guilt need an extra function for Ret, Heavy Burden, if the target is 15+ yards away they are also chained to the ground for 2 seconds.
Selfless Healer has to stack from Templar's Verdict along with Judgement for Ret.
Sacred Shield should absorb 20% more (for all specs really) completely undispellable for Ret.
Unbreakable Spirit's reduction effect per holy power spent should be doubled for Prot and Ret (2% ever 1).
Holy Avenger should be 1min cd, lasts 10 seconds.
Sanc Wrath should reduce the cooldown of AW to 2 minutes instead of having it last 50% longer.
Divine Purpose should be baseline for Retribution. Replace the ability with a talent that allows Holy to summon 2 guardians of ancient kings, Prot to become the guardian of ancient kings, and Ret to have a permanent guardian of ancient kings (this last one would be cc'able)
For the love of god, allow these talents to benefit from haste.