The arc subclass is called Striker. which is an offensive subclass meant to weaken the enemy with strong blows. Each subclass has a Super ability. Striker's is Fist of havoc, in which your character smashes the ground, dissolving enemies in a maelstrom of arc light.
Next up is Defender. This subclass is theme off of the titans at the battle of Twilight Gap and Six Fronts. In this subclass, the titans use the Super called Ward of Dawn which is a sphere formed out of void light that acts as a mostly indestructible shield. And finally, the most offensive subclass, the Sunbreaker. In this subclass, you "forge the fury of undying suns" and the super is titled Hammer Of Sol i which you throw flaming, explosive hammers.
"Destiny: The Taken King How To - Warlock Stormcaller Subclass Guide." Game Guides. N.p., 25 Dec. 2015. Web. 11 May 2016.