This sounds only like a dumb mix of Necromancer, Warrior, Paragon and Assassin.
Your Attributes sound not very good and your imagination of what they should stand weird is kinda weird
Visions = Shouts ? rofl
Caller of the Dark = sounds like an Attribute for summoning Shadow Creatures
Dark Hand/Assassination= omg, why didn't you name it direct Shadow Arts oO

but eh, I forgot, that belongs to the Assassin still.
This CC, like my foreposters said sucks atm, because its way too ununique - it looks too strong like a simple fusion of too much other existing classes.
The only new unique thign yet about your CC would be the Gauntlets as Weapons, but that again would be also too only a similar fightstyle in GW1, like Daggers then, so don't try to say only:
Gauntlets = 7-17 like Daggers..they should have somethign different, besides a different damage type, being Blunt and not Slash Damage.
There should be a reason, why people should take eventually in the end Gauntlets over Daggers.
Daggers for example have the Ability for Double Hits, what should Gauntlets do have ?
And when we talk about Dark Knights, attributes should look more like this:
[P]Might of Darkness
For every point in MoD the Dark Knight receives 2% Damage Reduction vs. Dark Damage and for every 3 points the DK receives every 5seconds (max 20E/minute) +1 Energy Heal, when a Stealth has startet.
Might of Darkness includes Skills about buffing yourself and Stealth Skills
Stealth skills would make the character as logn it doesn#t got "sighted" temporarely untargetable. These Skills get easily balanced by giving other Classes new skills, that enable them to sight enemies in stealth.
Rangers could get for example a nature Spirit, that sights stelaths enemies, that come the spirit too near, elemenalists could receive a water spell, thats about steam to sight stealthed enemies, going into traps of rangers/assassins would end stealth. Necros minions would be able to find stealthed enemies ect. Really weird, why they gave this easily balanceable feature not to Assassins, but however, so I give it the DK, so that he gets an unique feature and going into Stealth for DK's has something of using the Darkness to hide from, enemies ^^
Halberd Mastery
The DK's Weapon Attribute Nr. 1 for pure Melee Battles, using Halberd/Lance Attacks
Hands of Devastation
Weapon Attribute for your magical Gauntlets containing Dark Elemental AoE Spells, think of an Elementalist Attribute like Black Magic.
This Attribute has new Skill Types
Vision Skills. The Visions will be like self protective Skills for the DK and work like a combination of Perma Enchantment and Hex Skill.
While you target a foe with a Vision, you will receive for the cost of -1 Energy Reg. a positive effect, while your targeted foe will receive a hex Effect. The thing on visions is - only the targeted foe will be able to remove this effect by Enchantment Removal Skills, Hex removes don''t work, the targeted foe has to enchant remove the Enchant personally from the DK to get rid of the Hex.
Legions of Wrath
This Attribute contains either Skills to transform yourself into some kind of Half Demon or to summon Legions of Demons out of Box of Pandora, that will fight for you. and when you want to transform yourself into some realy mighty Demon, which woudl be the Elite Skills of the Attribute, you would have to sacrifice first some Legons for it to increase your Wrath Bar Level, until you have enough Demons sacrificed to become the chosen Demon. Skill Descriptions will tell then, how much Legions you have to sacrifice to transform into Demon X.
k, this may also sound like a simple Class fusion and i didn't want to erase the point of maybe having it a summon ability and i also think, the game needs somethign ,that can summon demons or can become self one for moments, but how I made it here, this Concept looks far more like something, that worth to be implemented, because its gameplay would be sure alot of fun having a kind of battle mage hybrid with similar gameplay to Chaos Legion, only with the difference that you fight here instead of Swords with Halberds and you will have the chouce, of you fight more melee, or go more on the magic line of the DK by using Gauntlets, which would be a nice different magic weapon, instead of ever only boring Magic Staffs.
Halberds/Lances:
17-32 Slash/Piercing Damage
With Halberd Type Weapons you can hit multiple foes, like with Scythes, but with slightly bigger range, not only adjacent, but nearby, because Halberds are longer than Scythes. WIth Lance Type Weapons you will be not able to hit multiple foes, but these come with an inherent Armor Peneration Bonus of 25%, because lances are the best Weapons for Armor Penetartion. They pierce through armors, like knifes go through butter.
Gauntlets:
11- 22 when attacking from distance (elemental shots), 7-17 Blunt Damage with the chance to perform a mighty Force Blow, that will knock down foes for 3 seconds
This way Gauntlets will be unique over Daggers, because they would offer the player the ability to change between melee battle and ranged battle and for melee they would have an other inherent effect, than double hits.
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HP: 480 (+25 when weilding Halberds/Lances)
Energy: 20 (+15 when wearing Gauntlets)
Energy Reg: 2 (+1 when wearing Gauntlets)
Armor: 70 (+10 when weilding Halberds/Lances)
Color: Black
uhm have I somethign forgotten ? dunno, you'll tell me if you find somethign.
What do you think of this type of improvements for this CC ?