A word on Last Word (Tanking Weapon comparisons).
I'm making this thread to park (and share) my thoughts on what I feel is a pretty worthwhile, but unfairly reviled tanking weapon. And also so I don't forget why I use it after a prolonged break from the game again, since it's a choice I end up having to defend a lot in-game. Last Word tends to be very widely regarded as vendor trash of sorts - at the very best, a placeholder. A cursory glance at the weapon leaves a very unfavorable impression in the mind of a prospective user, and understandably so. As someone who happens to be a big believer in the weapon, I feel strongly compelled to present (what I hope) is a good case for it.
The Proc
A good amount of people don't understand a few key things about its proc, so I'll start by outlining those:
1) So long as you're meleeing something with any regularity at all, the uptime on Last Word's buff is virtually 100%. It was deliberately changed to be this way following a hotfix early on. "The proc for the item, The Last Word, has been greatly increased to allow for continuous uptime."
2) How the proc works is it treats most incoming healing sources as if their caster had 300/340 more spellpower when casting them. Essentially, your healers get approximately 3 spellpower flasks worth of buffs whenever they're healing you. The effect this spellpower buff has on most healing spells is in the realm of a 4-5% increase.
Stats Comparisons
With that in mind, I'll proceed to draw some comparisons between Last Word and the much more sought after Mithrios, since the latter is generally perceived to be flat-out superior.
Focusing purely on the defensive benefits provided by both weapons, the comparison comes down to something like the following. This is (reasonably) assuming that Last Word's uptime is 100%, and that you gemmed a +30 stam into both sockets:
94 Stamina, 115 Str, +340 healer SP vs 113 (+6) stamina, 64 Str, 56 Defense Rating, 48 Parry Rating, 42 Expertise Rating.
Mithrios pulls ahead with a 25 stamina lead, a relative truck load of avoidance, and some very nifty Expertise. Last Word on the other hand provides about 42 Block Value more, assuming you have 5/5 Divine Strength (largely negligible), as well as obviously that curious healing taken increase factor. It should be established at this point, therefore, that Mithrios is quite clearly the favorable choice of the two if you happen to be tanking a boss that parry-hastes, or if the circumstances happen to favour having more avoidance over anything else. However, we know that when bosses swing absurdly hard and there's a good risk of them simply RNG-ing you into the dirt, consistent survivability becomes extremely important.
Survivability Comparisons
Mithrios' +25 stamina lead works out to about a +394 HP advantage, for a Paladin tank inside ICC. Mithrios appears to boast more EHP, in the strictest sense of the term. To see why Last Word might yet be preferable requires you to consider another nuance - remaining EHP at the moment of a potentially lethal hit, as opposed to simply max EHP. This is an argument that also applies to talents like Divinity and such.
Consider the following two postulates:
1) Most damage, by and large, does not one-shot you. Nor does it typically occur in short-enough intervals that it might basically amount to an insta-gib. Most mechanics with the potential capability of doing this are predictable enough for you to have been able to arrange a predetermined sequence of defensive CD usage.
2) Given the healing paradigms modern to late WotLK, the reality is that your healers are going to be constantly bombarding you with some kind of healing, and keeping you inundated in HoTs, and things of the nature of Earth Shield which cushion a sizeable portion of the next hit you take. When tanks do die, it's less because the flow of incoming healing stopped entirely, and more because the healing income stopped being sufficient enough to keep you up through a streak of hits, for whatever reason.
The corollary to both these points considered together is therefore that any increase to healing effects on you is also a direct increase to your balance EHP at the moment of a potentially lethal hit. If you're not getting 1-shot, and your healers always manage to squeeze in healing in between hits (even if it doesn't top you off), then the stronger those heals, the more EHP you actually have remaining on you while you're more likely to die.
Going back to Mithrios' +394 HP lead, we'll now try and work out how much extra healing you would have to receive between hits for Last Word's healing increase to out-scale the +394 HP of Mithrios. Conservatively assuming the spellpower increase from Heroic Last Word to work out to about a 4% increase in a spell's healing done, you would need to receive 394/0.04 = 9850 healing between every hit for Last Word to net you more balance EHP while in a prolonged health deficit than Mithrios would. This is a pathetically tiny amount when you consider the kind of HPS most tanks are constantly spammed with. A good amount of this will quite surely be covered by HoTs, things like ES, and the plethora of smart-healing that is constantly thrown around that will inevitably find its way to you. Even failing all that, the only thing you'd need is just slight focus from 1 healer out of 4-6 of them. It's easy to fixate on the fact that Last Word amps up overhealing numbers a lot without also considering that it drives up the most necessary healing too. So long as your healers realize that they should be constantly putting out some kind of healing on you when they have nothing else to do, it will virtually always be the case that the 9850 healing requirement is met.
Another point that very much bears noting is Last Word's synergy with things like Val'anyr, and the Divine Aegis talent. These are things that convert even over-healing to absorbs. For the duration of a Val'anyr proc, your Last Word therefore converts more of your healing income to direct EHP in the form of absorbs on top of your max HP, which is certainly a neat benefit. To a smaller degree, the same applies to spells like Earth Shield, Prayer of Mending, and Living Seed, all of which cushion away a small amount of the next hit you suffer, thereby also providing a benefit similiar to the one given by the shields, albeit in a more indirect manner. Earth Shield has a ~4 second ICD, so on an encounter like LK, after factoring in your avoidance, it's going to be activating on more than half of all hits, which is amazing. How frequently PoM activates depends on how your Hpriest is healing you, but if he puts it on you on CD, then it goes off about once in every 3 hits, maybe even more if it bounces back to you multiple times. Living Seed can be up as often as every other hit or even more if the Rdruid is constantly pumping Nourish casts into you, which he should be doing for the most part, outside of his assigned duties.
Of course, we know that Mithrios also has that aforementioned truck-load of avoidance going for it, but if your guiding philosophy behind your weapon choice is consistent survivability, Last Word is likely the better-suited tool to that end, more often than not. There are certainly times when you might indeed get one-shot (Shambling Horrors on p1, for instance), and in those cases an alternative like Mithrios or Ardent Guard might be better for the increased max EHP, as well as for the extra avoidance, since avoidance becomes the only way to increase your odds of living when damage received far exceeds your max HP. Mithrios is also better against Parry-hasting bosses, bosses which favour avoidance for other reasons, and it provides slightly more threat. Outside of these situations, I feel Last Word is the best general-purpose tool you can run for consistent survivability. You might argue that it's wiser to gear for the +394 HP in the freak event that you take repeated hits without actually taking any heals at all, but I would wager a lot that most of the time a tank dies, it's less because he literally received no healing for a small period (...which isn't to say that it doesn't happen), and more because he did receive some healing, but it just wasn't enough.
Spillover Benefits
Apart from the points above, Last Word also confers your raid with some pretty unique perks no other weapon has an equivalent to. These are termed "spillover benefits" because while they don't increase the user's own survivability directly, they do increase the survivability of someone else in the raid.
1) Last Word increases the heal transmitted to someone else via Beacon of Light. If the Holy Pally has his Beacon of Light on the Bear, and he casts a Holy Light on you, the healing increase you get from Last Word will also be received by the Bear, just as if he had a Last Word proc too. Because it's very common for a Holy Pally to be bomb-healing the off-tank directly while his beacon takes care of the MT, this is a perk your main tank might be fond of. Conversely, if the Beacon of Light is on you and someone else gets the direct heal, then it ends up not being buffed by Last Word, so that's something you need to be mindful of.
2) It increases the healing output of effects like Ancestral Awakening. Ancestral Awakening procs a smart-heal on the lowest HP raid member within reach of the Shaman based on how much total healing was done to the original target. An increase in the healing amount of the spell that was used to proc it therefore also increases the size of the Ancestral Awakening that procs either on you, or on someone else.
