I need not go into detail about how Rets are in contrast to other melee in arena, their representation is awful due to how much more powerful the other classes are. Currently in PvE they are also the bottom feeders of Melee, and that's sad considering Melee are almost always under casters.
This post is not about how bad Ret is, but how to make subtle changes to increase representation.
The first change is adding a "Stun Removal" to unbreakable spirit. As of now every Ret in the universe stepping foot into any sort of PvP will be taking clemency. With the 5.1 10% reduction to hand of purity, it will surely see some light against DoT teams however the other 80% of the time Clemency will be a dominant talent.
If freedom were to remove stuns like it did in WotLK, It would not only make the talent more popular versus certain comps but it would also allow Rets defenses to be buffed passively via how the talent currently works. Many classes much much stronger than Rets have the ability to get our of stuns (I'm starring at you, Hunters!) so I believe this to be a great idea.
The second change would be to buff PvP power to our heals. I'm aware that in 5.1, 25% of PvP power will affect heals. That is a barely noticeable change, however it's a start. Currently it is more suitable to spend holy power on a Templar's Verdict rather than a WoG, even with the glyph. Even popping Holy Avenger and switching to Seal of Insight, the current healing WoG does is simply not enough in Arena. What would be bad is buffing the direct healing to a point that Rets can keep their team alive forever, nobody wants that. Perhaps a way to solve this is allowing WoG to do a tremendous amount of healing but on a cooldown.
This is the current ret 4 set:
Gain a charge of holy power when taking Direct Damage every 8 seconds.
This, is garbage and could be replaced with something like:
Word of Glory heals for 100% more and always is guaranteed a crit once every 15 seconds
I think also making Divine Purpose baseline would improve things aswell as making Rets more competitive in PvE also however I see no way of doing that without having to rebalance the other specs