I first toon I had was an Arms, and I have over 35 days of "play" time so I kind of know what I'm talking about.
First, keep in mind that rvr is a caster/stealther game. As a tank you are there for protection and support, to take some shots so your casters don't and to take out the enemy's casters as soon as possible. What I'm getting at is that if you think having a "killer" spec means your going to be Rambo, try another toon lol. It aint' gonna happen.
At level 20, if you want to hit the hardest with one shot (lol like my arms, he's full pole) then I'd go with:
Pole: 20 For max damage.
Slash: 14 Needs to be about 2/3 of your pole to limit the variance of your damage output.
Shields 13 I know your full pole for max damage, but if you run around in rvr without a shield you will die quick, and your group will also die fast.
This is what I’d call the offensive-RVR poleman. You’re all offense for max damage, but still have the shield to block arrows and bolts, plus protect the real players in rvr, your group’s casters lol.
So what I do is run around in rvr with my shield, protecting the clerics and casters, then when I’m close to an enemy caster, wipe out the pole and go to work. And yes, if you get a caster or healer one-on-one, you’ll have np 2 shot killing them. One of the funniest things was in rvr when I ran around the corner of a keep and found 3 casters waiting there for some reason…I pulled out the pole and made quick work of them lol.
Lastly, get your armor sc’d and proc’d. To really be effective, you need max resist, especially since if your going up against a caster one-on-one, he’ll hit you 2 or 3 times before you can reach him.