Of course, the player Guardian can use abilities shortly after resurrection, but from a metagame perspective, it was evidently the developer’s choice to give us our abilities via a quick-progression tutorial in the first level rather than supply a lore-based explanation that would need to play out later in the game. With things like these, it’s difficult to decide where to separate them from the lore, so it usually depends on individual opinion whether we treat game mechanics as canon or not.
Looking strictly at the lore, there’s not much definitive information, but we do get a little bit of flavor here and there from things like subclass cards/lore entries and whatnot.
Shin Malphur was the first to use Golden Gun, and the way it’s written (from Shin’s own point of view) makes it seem like it was mainly on instinct.
As his tongue slipped between syllables my gun hand moved as if of its own will. Reflex and purpose merged with anger, clarity and an overwhelming need for just that… an end. In step with my motion, the fire within burst into focus – through my shoulder, down my arm – as my finger closed on the trigger of my third father’s cannon. Two shots. Two bullets engulfed in an angry glow. The other fell.
This is just one example, and really the only one we have that’s confirmed to be the first use of a Light technique, but I feel like there’s a lot to learn by taking a look at the way using Supers is described in the lore.
For instance, Wei Ning is quoted here describing what using Ward of Dawn is like for her, and her words echo Shin’s; they both name anger as a motivator.
“Be the Wall, they always told me. When you’re forming the Ward, imagine the Wall before you. Walk inside it, wrap it around you. That never worked for me. I just get really, really angry and then the Light does the rest.” —Wei Ning
Quick note on grenades and melee:
Shaxx is quoted saying he’d like to meet the Guardian who thought up using Light as a grenade.
“I don’t know who was the first Guardian to detonate their Light, but I would love to shake their hand.” —Lord Shaxx
Palm, the Warlock melee, is the only one that isn’t described in the grimoire like it’s just physical brute force. Instead, we get this, which seems to sort of set up willpower and hand motion as ingredients:
Curiosity gets a Warlock into trouble, and force of will gets a Warlock out. Even novices can shear reality with a single deadly gesture.
Back to supers.
Tevis has implied that the difficulty of summoning a Dusk Bow is linked to fearlessness of the Void.
“I’ve had a dozen Hunters ask me why it’s so hard to summon a Dusk Bow. I asked 'em what they thought of the Void, and their eyes told me everything. You can’t be afraid. That’s the secret. No fear.” —Tevis, Log Entry 19338
Continuing with Nightstalkers, Quantis Rhee gives an account of the Dusk Bow technique that seems to portray it as a really tactile process.
But Quantis knows how to find it—how to feel for the un-ripples of the Void, to draw Light from the infinities between spaces. She knows how to roll black holes between her fingertips, and how to nock her bow with the inescapable gravities of the universe.
In the Dawnblade lore entry, we see two Warlocks using a spoken incantation.
A young—by Warlock standards—apprentice holds out a hand and reaches for flame. Nothing. The wizened teacher laughs.
“You’re supposed to be teaching me. Not laughing.”
The teacher’s arm extends as one word hangs in the air, “Sword.” As quickly as it appeared, the blade vanishes.
“That doesn’t help.”
In a flash, the blade appears again, this time at the student’s throat. Both pairs of eyes widened. One aghast, one aglow.
“Say it with me.”
Two voices ring: “Sword.”
A blade appears in each outstretched hand. A pair of wings form on each Warlock’s back. Two Warlocks take flight and vow to never again look down.
The Arcstrider entry mentions that there might be a degree of physical buildup involved.
No one remembers who the first Arcstrider was. Hardly anyone remembers the Arcstrider at all. Time vanished us like it does memories.
But in the darkest days of the Dark Ages, when humanity was utterly defenseless, Arcstriders disciplined their bodies to let the Traveler’s energy flow through them, to call lightning itself to hand and wield it like a staff against the Darkness.
Sentinels seem to draw strength from determination.
Valiant heart, unwavering resolve.
I am a wall. And walls don’t move. Because walls don’t care.
Voidwalkers have probably the least information (at least, that I could find easily with a quick archive search) but Ikora has a quote that places Nova Bomb as sort of the same principle as a grenade, but with a lot more juice.
“A Voidwalker can detonate her Light in many ways. The Nova Bomb is simply the crescendo in a litany of explosions.” —Ikora Rey
Actually, Bladedancers get short shrift here. The most I could find was an allusion to the use of a moving trance.
Set aside your weapons and lose yourself in the blade trance.
Striker tactics seem to be mostly built around “turning your body into a projectile”; and are shown as technically similar with Bladedancer, i.e. galvanizing your armor with Light and speeding up your movements. The difference being Strikers detonate the built-up Light on impact in one big blast.
“Bladedancers lack the Striker’s strength, but even a Striker must admit the Bladedancers move at a velocity Strikers can only hope to match.” —Commander Zavala
“When a Striker turns her entire body into a projectile, no one is truly safe.” —Commander Zavala
The best we get for Sunsinger is:
Open yourself to the Light.
rip the old subclasses…
Anyway, most of these either tell us the process of using an ability, but not what it’s actually like, or give us an idea of what it’s like without really sparing the process any explanation.