Well Im not familiar with arena PVP; but protection wars can own in pvp battlegrounds if you know how to use them.
Here are some benifits
You can be a frontline fighter.
Your impervious to rogues and most other physical damage.
And if you organize your attacks, you can take out spellcasters with well timed shield bashes and deflections.
The only classes that can really ***** with a warrior is any intelligent
ranger, lock, or a good ice mage.
pallies... no! shield bash their heals