I enjoy fire the most by far, but I play it far differently than others in this thread have described. Arcane does the most damage, but it's awfully dull to just spam missiles, plus--as has been mentioned--you're very vulnerable to lockouts.
Here's my fire mage:
https://worldofwarcraft.com/en-us/character/velen/Vladrinor
Unbuffed, I have 415 SP and 41% crit. I have a set that gives me close to 600 SP when buffed, but I sacrifice nearly all the crit to get it. I'm awfully lethal with Combustion up in that gear, but in my experience, you really need a steady stream of instant pyros to do well. Without a decent crit rating, you aren't going to get many. I've found the gear in the above link to be an ideal mix, and 40% to be a good goal for your critical strike rating--much more than that, and you're sacrificing too much SP. I also don't run greater pyro, because my opener does more damage and has a 1 second cast time instead of a 4.5. It's a very mobile, high-damage, high-burst set up.
I run
https://www.wowhead.com/spell=203275/tinder as my PvP talent. It gives a nice damage increase and gives you about a one-second cast on your fireball. When used in conjunction with firestarter (which I've found to be the best 15 talent at 49 for fire BY FAR), you will usually crit for about 950. Chain that into a 650 fire blast (which gives you a hot streak proc), and you've already done more damage than a greater pyro. Most people have about 4k health. 35% of that is 1400. In other words, you can stand still for four seconds to hit someone for 1400 with gpyro, or (with Tinder) you can do more damage in your opener with a one-second cast, plus have an instant-cast pyro ready to roll. If the instant pyro crits (usually also in the neighborhood of 900), you've done 60% of the average twink's HP in two globals.
I realize Shimmer is the popular choice for endgame arena, but I've found Blast Wave to be a better pick (at least for me) at 49. Why? It gives a knockback with enough oomph to knock people off at LM or in EotS, but more importantly, it gives you another interrupt. Counterspell, DB, and Blast Wave make you a nightmare for healers. It can also function as a nice, instant burst with decent damage that can help you finish off someone close to death who might otherwise get a heal when your other instant-cast abilities are on CD. Additionally, there's one form of CC that's more common (and more terrifying--especially for a clothie) than all others at this bracket: stuns. Blink gets you out of stuns; Shimmer does not. Blink really saves your bacon against Storm Bolt and HoJ. I would consider running shimmer only as Arcane.
I save combustion for key fights when I need to delete a high priority target. Ideally, you'll have both stacks of Fire Blast up when you pop it (part way into your fireball cast), so that you can get an insane chain of crits to quickly drop an FC or healer in a team fight.
As to your other questions, dagger/OH is best--not only do you get the proc from dagger, but you also have double enchants, which leads to higher total SP. Frost is OK, but I've found it just can't quite hang with arcane on sustained damage or fire for burst and control.
Good luck, and feel free to add me if you have further questions, would like to queue some games, or need help gearing.
Svarazic#1199
