Before the Guide I shall introduce myself:
Who Am I ?
I'm Nerxqt Alliance Side on Warsong Server. I played since 5 years and I decided to do this guide because I think I've enough experience to talk about my class to help new players.

Before I start just a little warning: I'm a French Canadian so if you see some grammar/spelling mistakes its normal. I'm not bilingual and I will thank you a lot if you can leave a comment and tell me where's my mistakes so I can correct them.

What's an arms warrior?
Arms warrior is a two handed wielder that deal damage. Arms warrior is the best spec for warrior in PvP. Arms Warrior is a cool spec because they have good snare, stun (45cd), anti-root(Bladestorm), fear, spell reflect, charge and a lot of other useful spells that make the spec so fun to play<3.
So let's start.

Specs
They are lot of viable specs. I'm going to talk about these specs:

The Normal Slam Spec:
http://wowtal.com/#k=vzb_-1e1.bqj.warrior.


This spec use Improved Slam instead of Drums of War. If you prefer you can move the two talent in blitz into Incite.

Pro:
Piercing Howl + Improved Harmstring
Blitz(if you use it)
Improved Slam = continuous damage on your target.

Cons: No Drums of War so no interrupt/fear if you are out of rage.

The Normal Heroic Strike Spec:
http://wowtal.com/#k=VcbsEBgL.bqj.warrior.

This is the heroic strike spec with Incite.

Pro:
Piercing Howl + Improved Harmstring
Incite give you an extra crit with heroic strike when you crit with this attack.

Cons:
No Drums of War so no interupt/fear if you are out of rage.
Blitz 1/2 is fewer rage when charge and you can't stun hunter + pet + his mate in arena.

The Silence Spec:
http://wowtal.com/#k=G23sHM3U.bqj.warrior.

This spec is mainly useful in arena to silence healer with Heroic Throw and Shield Bash.

Pro: 3 Sec silence
Improved Harmstring
Incite
With this spec you can refresh Rend with Thunder Clap
and put a debuff that reduce attack speed.

Cons: No 15 yards snare, no drums of war, no improved slam.

Glyphs:

Prime:
I use Glyph of Bladestorm, Mortal Strike, Overpower as prime glyph for my spec. You can change Bladestorm Glyph for Slam one if you play Slam Spec.

Major:
I use Glyph of Long charge, Rapid Charge, Piercing Howl are the one that I prefer. Major glyph should be used for your own play style because they don't change the game play a lot compare to prime one.

Minor:
Your own choice, I use Glyph for my shout and for berscerker rage. Choose them for your play style.

Stats:
At least 5% hit, I use 20 expertise to reduce dodge/parry by 5% but some people don't.

Hit Cap > Expertise Cap(optional) > Strength > Crit > Mastery > Others stats

Resilience: I personally suggest using 3k+ when you start arena.


Gems:
For gemming some people prefer full strength everywhere and some prefer to get bonus. I prefer to get bonus.

Red: ALWAYS I REPEAT ALWAYS put red strength gem.
Yellow: Strength or Strength + Crit.
Blue: Strength or Strength + Stam/or hit or Other Gem for your cap.

Reforge:
Reforge Haste, Mastery, Hit/Expertise(if capped) into Crit.

Enchants:

Weapons: Landslide or Pyrium Weapon Chain if you don't have 4 piece pvp bonus.
Bracer: Major Strength if you are Hit capped, Precision if not.

Chest: Resilience or +20stats as you wish.

Cloak: Greater Crit.

Feet: Lavawalker or Assassin's step or Earthen Vitality for 8% speed bonus

Gloves: Mighty Strength

Belt: Ebonsteel Buckle give you an extra socket so just put a Red Strength gem.

Head: Arcanum of Vicious Strength or PvE one if you don't want more resilience.

Legs: Dragonscale Armor

Shoulder: Greater Inscription of Vicious Strength


"Rotation":
In PvP there is no rotation but people that start always like to know what to do first.

Charge > Rend> Mortal Strike > Overpower
I suggest you to use Harmstring after the charge stun.
Always keep Rend/Harmstring up.

Macros:

This is the classic Shield Wall macro.
Useful to keep you alive when you take to much damage. To avoid burst. Etc.

#showtooltip Shield Wall
/cast Defensive Stance
/equip "Your one handed"
/equip "Your Shield"
/cast Shield Wall

The spell Reflect macro.
I think its my favourite macro. I put two time /cast spell reflection because for me its easier to spam and I don't know why I get less equipping bug and ****. A little tips when someone cast a spell vs you. Press it one time then wait when the cast is about to finish press it again. If you do that correctly its going to be harder for your enemy to cancel his cast.

#showtooltip Spell Reflection
/cast Battle Stance
/cast Spell Reflection
/equip "Your one handed"
/equip "Your Shield"
/cast Spell Reflection


Classic Disarm macro.
Use it to disarm enemy. This macro is simple, just going to switch defensive stance, then disarm. After that go back to Battle Stance but you need to spam it a bit because of Global Cooldown of your stances.

#showtooltip Disarm
/cast Defensive Stance
/cast Disarm
/cast Battle Stance

Shield Block macro.
This is a classic shield block macro I personally don't use it a lot because shield block have only 25% of blocking and vs melee class I just don't get the time to do it. I just put it in my defensive stance if I need it when I've the flag in Warsong. If you think you are going to use it and you prefer an auto switch to defensive stance just add /cast Defensive Stance before /equip "Your one handed".

#showtooltip Shield Block
/equip "Your one handed"
/equip "Your Shield"
/cast Shield Block


Stance swith macro

Battle stance:
Very simple macro switch to battle stance and equip your two handed weapon.

#showtoltip Battle Stance
/cast Battle Stance
/equip "Your two handed weapon here"
/cast Battle Stance


Defensive Stance:
Same as the battle stance macro, just equip your one handed + shield instead.

#showtooltip Defensive Stance
/cast Defensive Stance
/equip "Your one handed"
/equip "Your shield"
/cast Defensive Stance

Berserker Stance:
Same macro as battle stance one, just change to berserker stance instead.

#showtooltip Berserker Stance
/cast Berserker Stance
/equip "Your two handed"
/cast Berserker Stance

Intervene Macro:
Simple macro, target the nearest friend player, then intervene him, then target the last target. Very useful in arena to intercept enemy spell that are cast on your mate.

#showtooltip Intervene
/targetfriendplayer
/cast Intervene
/targetlasttarget


Mortal Strike macro:

This macro start to attack your target, then equip your two handed weapon, then cast Mortal strike.

#showtooltip Mortal Strike
/startattack
/equip "Your two handed"
/cast Mortal Strike

Deadly Calm Macro
This is a burst macro, it cast deadly calm, then use your trinket + racial if you have one.

#showtooltip Deadly Calm
/cast Deadly Calm
/use "Trinket"
/cast "Racial here"

Pummel Macro
With this macro I cancel bladestorm so I can interrupt.

#showtooltip Pummel
/cancelaura Hand of Protection
/cancelaura Bladestorm
/cast Pummel


Charge Macro
Same as pummel macro but for charge if the target flee when you use bladestorm you can cancel it then charge.

#showtooltip Charge
/cancelaura Hand of Protection
/cancelaura Bladestorm
/cast Charge


Heroic Leap Macro
With this macro the green circle don't disappear when you spam your spell.

#showtooltip
/cast !heroic leap

And the last and best offensive macro for warrior is:
One Shot Macro
use this macro wisely because with this macro you are going to take a lot more damage but you are going to do lot more damage.
Tips: Please don't waste this macro on a rogue/warrior/shadow priest that didn't disarm you yet.

#showtooltip Bladestorm
/cast Berserker Stance
/cast Recklessness
/use "your trinket"
/use "your Racial"
/cast Bladestorm

Stun Focus Macro (Warsoul idea)

Basic Stun Focus Macro so very easy stun your focus when you use this macro. (add /cast Throwdown after if you want to stun your Target when you don't have focus)

#showtooltip Throwdown
/cast [@focus, exists] Throwdown

Fear Focus Macro (Warsoul idea)

Same as Stun Focus Macro fear your focus when you use this macro. (add /cast Intimidating Shout after if you want to stun your Target when you don't have focus)


#showtooltip Intimidating Shout
/cast [@focus, exists] Intimidating Shout

If you have any question about this class, need a little precision on somethings, need to duel me, etc... just whisper me in game or leave a comment or Private Message me.
If you want to add something to my guide or you think I'm wrong just leave a polite comment and explain your view point. Thank You.