First of all, heroics aren't the best place to analyze stats like this because raid bosses require a higher cap than your normal heroic 5 mans. 8% hit and 26 expertise are the cap, though the need for reaching 8% hit isn't great enough to be gemming hit. You shouldn't be gemming for 20 hit and only use hybrid hit/gems if the socket bonus is 9 stam (if you feel you really need the hit), otherwise 30 stam is better. I'm not positive but I don't think you can ever prevent glancing blows. There is no cap on strength and I don't know why they would be gemming for strength except for more threat, but it shouldn't be necessary. Seal of Command is great for trash and aoe tanking but Seal of Vengeance/Corruption is for single target. At the very least grab the glyph for sensing undead for 2% more damage, but I don't see a reason not to have the lay on hands glyph as well. If you do a lot of ICC tanking I would take some points out of Conviction and put them in Crusade. I would swap out your Judgement glyph for Divine Plea, and the taunt glyph is only great for bosses that require taunt rotations/tank swaps. I would fill it with either Hammer of the Righteous or Salvation if you want another CD to use.