I have done of thinking about my time on live and RoR as a Black Guard, what makes them powerful, why they have the reputation they have and why the adversity to a KD, and why it is so hard to give up the shield.
Sword and Board Strengths: The sword and board black guard is increadibly powerful, has access to alot of goodies, and still has alot of survivability. This is what the ultimate SnB spec looks like in Tier 4.
http://waronlinebuilder.org/#career=bg; ... :;;0:0:0:0:
It's a No-Brainer, you get all your toys, an amazing wounds debuff, tons of crit, still survivable, heal debuff. 5 second KD. In T3 most BG will go Pure Anguish because of how much utility it brings. In T3 The Malice BG is a melee train assister, but loses much of his killing power without access to Anti-detaunt and heal debuff tactics.
Two Handed-Knock Down No Go: The reason why there is so much resistance about giving the BG a two-handed KD is simple. Their two hander spec is gives too much DPS to give the BG a further form of CC. The arguements which say that BG SnB is too good to let them have a 2h KD is irrelevant here. But the former point has merit.
Why is the T4 2hander Black guard so powerful? It's actually simple, it's not 1 tactic but 3-4 tactics together: Hastened Doom, Filled with Fury, Unstoppable Fury, and Soul Killer. The peak of BG DPS is when a BG can spec all 4 of these, (sometimes switching one of them out for Rugged), combined with Choking Fury a SnB or 2h Chosen is a force to be feared.
Knowing this the Black Guard can have some subtle changes to their masteries which can grant a support spec for a 2hander Black Guard that allows him to sacrifice pure damage output for utility and support. We also can use this as an opportunity to make the Loathing Tree more enticing as opens up many different spec styles.
Here is my suggestion:
Elite Training: Malice 6pts
Force of Fury: Anguish 10pts
Blade of Ruin: Loathing 10 points.
As for Blade of Ruin: I would suggest the following: Have the opponent do less damage for the duration of the Dot AND if you have a two hander equipped you Knock down the target for 3 seconds. The Seething power of the strike is more effective the more force you put behind it.
Alternate Specs: What this does do is leads to Loathing being an alternate tree: adding more to group utlity while not subverting the power of the Black Guards ultimate spec.
Opportunity Cost:IF the black guard wishes to go full bore and get his beloved 4 tactics he is unable to get the Knock Down. Force of Fury is a lack luster ability and might be re-adjusted later but the Anguish tree is so good that it can make this concession for now.
This will open up options for Black Guard to go 2 hander yet makes him choose what he wants to bring to the party, instead of the one-TRUE spec that competetive T4 BGs will have.