You do not want to go for the dual wield hit cap as frost. Just shoot for the yellow cap, which is 5% (about 164 rating) after Nerves of Cold Steel.
The two expertise numbers are for your two weapons. I am guessing that you are a human and your main hand is a mace or sword (therefore granting you +3 expertise with that weapon) and your off-hand is an axe.
Note that if you are not having threat issues, neither hit nor expertise is an important stat as a tank. So the question of whether your expertise is high enough hinges solely on your personal experience. If you are having problems with threat, you may want some more, otherwise just get stam and armor.