I'm just going to start at the head of the post and work my way down...
At the top it says x25 might stacks, this makes a reader assume that you can not only get those stacks, but keep them as well. Fact of the matter is, the only time you would ever get 25 might stacks with this build without major group support, is if you had out the Greatsword. Even if you do have out the Greatsword, getting 25 stacks is highly improbable. You don't use Signet of Rage for the 5 free stacks, you barely have any boon duration so "For Great Justice!" is only giving you three stacks. You get 4 stacks of Might from your Elite on a ridiculous cooldown, the 3 from "For Great Justice!", and 5 second stacks from Forceful Greatsword every time you crit. If you think that even matters, think again, as a post by Lilitu explains:
That is accurate, self explaining math that anyone should be able to follow. Add up the sources (4+3+5 = 12), and you get 12 stacks of Might (During Battle Standard, and if you are constantly attacking with the Greatsword only) and that's if you have 80% Crit, which this build does not. If you add up all his gear choices (Assuming Ruby Jewels in armor), you get 74% crit with a constant Fury buff. That said, I don't see any way that this build would achieve constant Fury either. You get it for the duration of Battle Standard, and you get 8 seconds from "For Great Justice!", testing shows that the Fury gained here ends after 112 seconds, making Fury up only 8 seconds every 25 for the last 80 seconds. This ends up being ~26 seconds of Fury if I am not mistaken, adding that to the 112 and then dividing by 192 (Banner CD) gives us a Fury up time of ~72%, far from constant. You could supplement this number slightly by using the Greatsword burst skill (Generally accepted as an awful idea, and in any GS build you should be taking Berserker's Power and/or Heightened Focus) but that would take away from your Might stacking as it is a slow hitting skill.
Next is the the screenshot which, as commented on in Lilitu's post, is a "little misleading". The screenshot does not belong to him, as far as I can tell he did not ask for permission, he did not credit the owner, and most importantly I believe it portrays a build that is not this one. If I am seeing this right, it reflects another member's build, which is more damage oriented.
Lastly in the header, a point in your favor, the shield should also be accounted for in your "Traitable Weapons".
Next is the "This build offers" section, in which he states that the build is capable of great damage, great survivability, great control, great mobility, very good condition removal, and the ability to use 6 weapons to their full effectiveness.
The build does not provide "great damage" it provides good damage at best. With 30 points in Defense and less than 15 average might stacks, you definitely aren't doing anything "great" in this regard.
Great suvivability is something you don't have either. With the amount of points you sacrifice to damage in leu of defensive stats, you're only ending up in the "good" section here, too.
Great control and mobility are both relative to the current build you are using (As well as damage, matter of fact..) and you can't really say that your entire build has all these things seeing as it's three seperate builds meshed together using one trait set and 8 weapons. I also wouldn't call your control "great", however the mobility is pretty high due to Signet of Stamina (Which you for some reason remove from the mobility build).
Very good condition removal is yet another overstatement. You have Mending to remove two, and Signet of Stamina (In 2/3 builds) which removes all of your conditions. Problem is, you would only ever use that Signet if you had many conditions since it is on a 36 second cooldown (Traited). Not to mention, in most scenarios you would never gain more than two perhaps three conditions to remove.
Lastly in this section, we have the "ability to use 6 weapons to their full effectiveness." Now I think it should be common sense here that you are not using these weapons (Any of them) to their full effectiveness. You are putting so many traits in all these different ares that nothing is really effective any more. It's simply a very versatile build, but you aren't supposed to be this versatile. Any good build focuses on one or two aspects and creates synergy between them. A support build uses healing/survivability and control, things that compliment each other. What you've done, is taken a fine dps weapon like the Greatsword, and placed it on a mostly tanky build. What this means is that your Greatsword is providing nothing to your build, it's not increasing the effectiveness of it in any way.
This goes the same for all weapons, control sets need you to be more tanky so you can actually stay in and control, condition sets need condition damage and duration, etc.
You say in the build that there is "no weapon setup that alone is capable of dealing with every single situation in the best way". This is certainly true, but you aren't expected to handle all of those situations for your team. Each team member has a duty, rather than have your sub par control skills or dps skills, a team should have a main damager and a main controller. The max efficiency controller allows your role as damager to remain at max efficiency as well. This way is much better, as a "middle-man" build is not effective for you or your team (And can often hurt team dynamics).
Knight's gear is fine, and so are all your other gear choices, except Soldier's runes. At no point ever should this build sacrifice six rune slots so that it's one shout (In only 1/3 builds) can remove one condition every 20 seconds. Not only is that a ridiculous waste, but you gain even more defensive stats that aren't needed.
You use Signet of Fury on a Control build simply for the purpose of gaining adrenaline, which is a monumental waste.
I'd like to point out at this point that your Control build retains the Vulnerability on crit and GS traits in Arms, which are incredibly worthless in such a setup (In fact, all of Arms is practically worthless). Not to mention in your Mobility set you retain the Shield trait which is again, wasted.
You use one pathetic banner, which you have augmented with a trait. You use a two Signets (Though only one in each build) that should remain of cooldown, and have augmented them with a trait to reduce it's cooldown. You have a single 5 second Endure pain stance in one build, and an 8 second Berserker's stance in the other two as well as Frenzy in the last. You have augmented these Stances with 25% duration, increasing Endure pain to 6 seconds, Frenzy to 5 seconds, and Berserker's to 10 seconds. You use one shout in one build that you suggest augmenting with Soldier's runes.
I'm not sure if you noticed, but that's 3 traits and a full set of runes gone to augment each separate skill on your bar. That's not even counting all of the traits you have put into all of your different weapon types (Some of which go wasted completely, the others remain ineffective for the build).
Basically what you have here is a mix-match of skills and traits to support a build philosophy that should not exist. You should never be prepared for every situation, that's like asking a soldier to be trained efficiently in every single type of combat. There may be some that can do it, but a master of 2-3 weapons will always come out on top. You need to rely on others to bring the things your build can't, and you need to build for whatever is most effective for your playstyle.
Build effectiveness is NOT a linear relationship. What this means is that by putting a Greatsword on a full cleric's shout build instead of Mace+Shield, the damage I receive is NOT equal to the defense I lost. This is because the control/defense of Mace+Shield synergizes with the build and increases it's effectiveness, whereas the GS does not have such synergy. The same thing would happen if you put a defensive weapon on an offensive build.
In essence, this build not only lies about a fair number of details, but the details that are true aren't effective in any way. An optimal build is not one that can do everything, it's one that can do a specific thing that your teammates benefit from. Then your teammates have that same option, and can create an effective build that you benefit from.
Instead of having five people who are decent at everything, you get five people each with a specific task, and by doing so group dynamics, social experience, and efficiency all skyrocket.
That's my two copper on this build, again I will say this is not to flame or bash, just putting the facts out there. I realize this is a very long post, and it did take some time to write. Therefore I would appreciate people to read it thoroughly, and upon such a point that they would like to post their thoughts to please make them respectful, mathematically sound, and detailed.
If you have an opinion please state it, but keep in mind all of the math here is correct, and you can test it. All the thing's I've said are very true as well, and as such I'd not like to see people saying, "Brand is wrong, this build is great!" The fact if this build works or not is not the argument I am making. I am simply saying that it is not optimal or effective by any definition.
Look forward to replies, perhaps some people will recognize this build's flaws, lies, and inefficiencies as I have.