Death Knights have it pretty good in PvP. Thanks to big whomping two-handers and magic damage strikes and spells, you can do massive burst damage and tear through armor defenses pretty easily. On the control front, you have Strangulate, Mind Freeze, Chains of Ice, and, depending on spec, maybe even a few other ways to silence, slow, or shut down an enemy player. Finally, the plate armor and defense cooldowns assure that should you the unlucky target of the burst train, you can hold out a lot longer than many.
Still, it's not just being a Death Knight alone that gets you PvP fame and godhood. It does help to have the right talents, gear, and strategy. So WoW.com is going to talk about that a bit, focusing mostly on the talents. Here's two popular PvP Talent builds.