Except for improved righteous fury, that's pointless. Gonna put those 3 points into Shield Specialization.

Righteous fury is mathmatically better than shield spec unless you're wearing tank gear with lots of block rating.

Shield spec is only 30% less damage when you block. Righteous fury is 6% less damage, constant.
Factor your block rating into that and you realise you have to literally be wearing almost entirely tank gear for shield spec to mitigate more damage overall.

Think before you type.

Then why take Redoubt at all?

Because it's a better choice than Improved Devotion Aura, which you are not going to be using in the arena, and, frankly, is a pretty crap talent to begin with. On the other hand, if you're a healadin, there's a good chance you're carrying a shield to begin with, so Redoubt probably will be a help to your survival.

Also, you can't block while casting. So, unless you're just running around, or meleeing, block-buffing talents won't help you as much as a constant 6% damage reduction, which applies not only to melee, but to spell and ranged damage as well.