Ergo Sum

Perks (possible rolls, from game data)
Intrinsic	Wolfpack Rounds Gathering Light Sacred Flame The Perfect Fifth Arc Conductor Stormbringer Unplanned Reprieve Insectoid Robot Grenades
Blade	Hungry Edge Enduring Blade Honed Edge Jagged Edge Tempered Edge
Guard	Balanced Guard Burst Guard Enduring Guard Heavy Guard Swordmaster's Guard
Intrinsic	Vortex Frame Caster Frame Wave Sword Frame Lightweight Frame Aggressive Frame
Trait	Transcendent Duelist

Ergo Sum is an Exotic Kinetic Sword from Destiny 2: The Final Shape (Season 24) that sits in the Energy slot.

Intrinsic perk: //Gathering Light//. Final blows grant stacks that can be spent by reloading to restore melee, grenade and class ability energy, scaled by stack count.
Curated roll: Tempered Edge blade, Burst Guard, Wave Sword Frame and Transcendent Duelist (faster Transcendence meter, extra damage while Transcendent).
Random rolls can carry the intrinsic of other Exotic weapons (for example Wolfpack Rounds from Gjallarhorn or Stormbringer from Cloudstrike), per PC Gamer.

Quest: complete Destiny 2: The Final Shape campaign, the "Queens I" mission, and the quests Lost in the Light and Found in the Dark. The follow-on quest Destined Heroes takes you into a new zone of the Pale Heart and awards a curated copy.
Farming rolls: random drops from the Overthrow public event (final chest, high chance per the guides), plus the weekly Pathfinder card.

GameSpot's guide covers an Ergo Sum catalyst; its exact requirements were not verified for this page.

How to obtain