You're basing everything off the 3man arena team, but using the pre-expansion talents?
Am i missing something?
edit: and in 3man arena's you wouldn't need so much stam / armor gear.
that's only needed when 3+ people are nuking u, 2 of which are a warrior and rogue..
If you want to 3man pvp in arena's
now though:
In a 3man team, it would be very very hard to overlook silence. I would think about a build more like
http://www.wowhead.com/?talent=bxMGR0bZbxtZVMGdcd , unless of course your mage isn't going an AP build, but i doubt that would be the case in a 3man team.
Silence, Imp Mana burn, Holy Nova > * for a 3man team.
Obviously, i've more looked at the fact that you're in a 3man team, rather than your whole "Holy Nuke build". Cos holy nuking in a non-controlled environment is fairly rubbish (as already stated)
edit: also
* Improved PW:S to help keep the warrior alive, despite the slight reduction in rage generation it causes.
(especially in 3man, best to keep this off the warrior and on the mage :) )
* Force of Will and Holy Specialization to get 10% more crits on my heals, Smites and Holy Fires.
(FoW doesn't effect your Healing spells)
* Force of Will and Searing Light to get more damage output on my Smites and Holy Fires. (How do these stack, btw?)
(Yes the stack)
* Holy Reach to be able to heal and DPS from further away.
(So you can... Prayer of Healing from further away? :P )