During the Bungie Showcase, Dave Samuel states that Light is about "creation", while Darkness is more about consciousness. The latter was specifically in relation to Strand, which involves manipulating the alternate psychic universe/weave that connects all living things. Before Strand, I initially thought the Darkness subclasses would focus on "destruction". For instance, a "Decay" subclass would force the radioactive decay of matter until it was reduced to the most fundamental particles. However, the more I thought about Strand, it eventually clicked for me what the theme of Darkness actually is.
The Darkness isn't about "destruction"; we use the Light to vaporize helpless ads down to atoms all the time with Light abilities. The Darkness is about "Shape".
Stasis was the first Darkness subclass we wielded. That it functions by removing energy from a system initially fed into the "Darkness is destruction" idea, as Stasis "destroys" energy rather than "creates" it. However, the result of Stasis removing energy is the creation of crystalline structures, potentially perfect crystals, a hypothetical structure created at Absolute Zero. It is the removal of entropy from a system to create a specific "shape" out of that system.
Strand will be the second Darkness subclass we wield. From what the Showcase showed us, we can use the psychic energy of the Weave to "Shape" psychic constructs, create sentient creatures (Architects), or even sever enemies from the Weave entirely (Tyrant). Whereas Stasis "shapes" matter into crystalline structures, Strand is used to "shape" psychic energy/matter from the Weave into whatever the wielder desires.
Then there is the Taken power. While we now know the Taken power is derived from a greater power - The Witness has the power to move worlds from one reality to another - the Taken thoroughly shows how the Darkness is about "Shape". You just need to do a before and after comparison of a Taken enemy to their regular counterparts. [url=https://www.ishtar-collective.net/entries/osmiomancy-gloves]As the Osmiomancy Gloves tell us[/url]: "[i]Taking involves [b]reforming matter in a self-contained reality, where the creator defines past, present, and future[/b]; imagine how a more insightful being could expand these definitions, to different ends."[/i]
We also have Deepsight, a power that ties strongly into the Darkness being about consciousness. We use Deepsight to see through illusions, make solid echoes of past events, and we use it in tandem with the Relic on Mars to "shape" weapons we learn to craft through Deepsight Resonance. Savathun created that room in her Throne World for us to reveal her memories, and it is even implied she used it to restore Crow's memories.
It appears to be lesser forms of Darkness-derived power that focus more on destruction - Hive Magic, Corruption, the Weapons of Sorrow. Fascinating concepts to consider and imagine Darkness subclasses for. But Hive Magic and the powers stemming from it derive from the Worms and the Worm Gods. The Worm Gods say so themselves in the [url=https://www.ishtar-collective.net/cards/xvi-the-sword-logic]Books of Sorrow XVI: The Sword Logic[/url]: [i]But you are armed to respond in kind. Savathûn’s mothers have listened carefully to our teachings. [b]We will not give you the Deep, King Auryx — that power is for us, your gods. But we will teach you to call upon that force with signs and rituals.[/b]
Small minds might call it magic.[/i]
As far as the Luster and Resonance used by Rhulk are concerned, It certainly is Darkness power, as Rhulk is a Disciple of the Witness. It appears to be pure Darkness power as channeled through Pyramid technology; the Shadow Legion in [i]Lightfall[/i] will use similar Light-suppressing technology.
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I've already made this post long enough, so I'll try to write a short conclusion:
As the philosophy of the Darkness revolves around the Final Shape, the powers derived from it revolve around "shaping" the environment and world around them, in ways to better allow their wielders to become "The Final Shape".
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Dave Samuel is a VFX designer, so I don't think he meant it to be that deep. It seems to me like he was just looking at it in overarching themes, creation being taking the light & turning it into other forms of energy, & consciousness being learning about something & interacting with it.