We just deployed a hotfix to modify Holy Wrath so this spell has the same diminishing return mechanics that other player stun spells and abilities currently have. This will prevent Undead creatures that we wish to be susceptible to stun from being permanently stunned if you include enough Paladins in your raid who then rotate their Holy Wrath casts.
This will affect the difficulty of Anub'arak, but we didn't want the "right way" to defeat this fight to involve bringing five Paladins who glyphed their Holy Wrath spell.
I'm not exactly sure how Holy Wrath's stun diminishing returns were overlooked for this particular fight, the new Glyph and nature of this encounter seemed tailor made for each other. Using Holy Wrath rotations to deal with otherwise near untankable adds is innovative and a different role from those Paladins are used to (especially Holy Paladins). The method also changes up rotations significantly, no bad thing for bored Rets. But hey, if it trivialises content or makes stacking a particular class necessary I guess a hotfix was required.
Anyway, the upshot of the hotfix is that the Glyph of Holy Wrath is no longer useful due to these diminishing returns, the DPS increase of choosing it specifically over another Glyph option probably isn't that high given GCD conflicts. In fact, other AoE stuns such as Shockwave and Shadowfury should now see greater use in this particular encounter, making Holy Wrath of limited use yet again except for the damage.
Was Paragon's four Paladin World First really trivialising it?
No small number of guilds are going to have to re-think their Anub'arak strategy, and it puts something of a pall over the two 'World Firsts' if they 'abused' Holy Wrath in this way, this screenshot indicates that Paragon used Holy Wrath extensively. Perhaps the real rush to the final World First in Heroic Mode can now start.
As an aside, the number and frequency of Paladin hotfix nerfs really serve to justify the opinion that some of the encounter Devs don't have much of a clue of Paladin abilities. That doesn't exactly fill me with optimism given the current development of a new expansion.