Warriors are extemely OP. Warriors haven't been a fun class to play since WotLK imo. Warriors can literally make 2 or 3 burst macros and spam them. Although this doesn't take much skill, it is what most do and why any noob warrior is easily killed! CC them for the first 10-20 seconds until all their buffs wear off and they melt like butter. As far as DK, If you roll frost 2h will provide you with more burst for PvP, just be sure to use obliterate on your killing machine procs and don't waste it on frost strike. DW frost does provide much higher sustained dps for PvE, but in a PvP environment you will most likely always be moving so its hard to sustain up time on your target for DW to be viable in PvP. It may be ok against other melee classes but not enough to say it is better for PvP. Both provide peels and utility to any comp for arena. My advice would be to try both and play whichever you like more. Personally I think warriors are boring and prefer DK. I switch between 2H Frost and UH. Both are different play-styles and provide different utility. What works better depends on your comp imo. If you already have a partner that has good cc then I don't think uh is going to shine where 2h frost's burst will be much more viable. What makes a class good is the player! Practice, read, watch videos, cross reference, and practice some more! Don't ask the community because you are going to get personal opinion and rarely anything that is fact based! You can't even rely on the bug tracker because not all class bugs posted are truly bugged talents and are nothing more then speculation and/or assumption.