You don't use Shield Slam on CD. Always use shield slam on CD. on a single target fight ~35% of your total damage should be from shield slam. SHield slam is your hardest hitting ability, it generate on average the most rage of any ability in your arsenal, it enrages you, it procs Ultimatum.
Your shield block uptime is appalling. Doesn't matter how you gear Mastery, stam, avoidance or even gods help you crit, your shield block uptime should be somewhere between 50-66% of the total fight. if something is hitting you, so pretty much every boss except Lei Shi in ToES you should be spending most of your rage on shield block. Forgoing shield block is a massive RPS loss, survivability loss and if you take glyph of heavy repercussions, as you do, a huge DPS loss.
Stop casting Heroic Strike or Cleave if you don't have an ultimatum proc. Once again this is a massive RPS loss, survivability loss and if you take Glyph of Heavy Repercussions, as you do, a huge DPS loss. your HS hits for 38k, your SS hits for 145k. Shield Block cost 60 rage, HS cost 30 rage so you get half as many Shield blocks as you would Heroic Strikes, with the glyph SS will hit 50% harder. You will get 1 SS per shield block at minimum, (it works out to be ~5s cd on average, but we'll ignore that). 50% extra on SS is 73k, 2 heroic strikes are 74k. Doesn't work out does it? Except now you have a much higher chance to crit block which means a much higher uptime on Enrage increase all damage by 10%. and giving you 10 rage. so if we assume you have 45% avoidance after boss suppression you're going to average 1.15 crit block per shield block so 11.5 rage. so you don't actually get 2 HSs for 1 shield block you get ~1.6, so 68k for HS or 73k for Shield block.
As you take Glyph of Hold the line, do not bother trying to balance your dodge/parry, go full parry, red sockets should be parry, blue should be parry stam, yellow should be parry dodge. unless you don't want the socket bonus in which case they should just be parry.
Use recklessness on CD, and where possible line it up with avatar, the first time you get aggro you should have both up.
Use Every Ultimatum. there's at least 3s between shield slams. If ultimatum procs use it right away.
Stick River's Song on your Main hand, ~3k Dodge (which turns into crit) is better than strength (which doesn't turn into crit) but turns into ~3K AP which doesn't buff your Shield barriers. You probably sitting around 300k AP so its 1% AP gain vs a 3-5% crit gain, and a 2-4% avoidance gain.