Light

Were you looking for The Traveler's Light? Light is a Guardian attribute that increases the damage done by subclass abilities and weapons and decreases damage taken. A Guardian's Light is calculated as a weighted average of all equipped items.

Calculation
The following table illustrates how each piece of equipment contributes to the Light level:

Loot Sources
The following can drop gear up to Light level 365:
 * SIVA Strike Playlist

The following can drop gear up to Light level 385:
 * Rare engrams
 * Wrath of the Machine (Normal)

The following can drop gear up to Light level 390:
 * Legendary engrams
 * Heroic SIVA Strike Playlist
 * Trials of Osiris Gold-Tier bounties

The following can drop gear up to Light level 400:
 * Exotic engrams
 * Reputation rank-up packages (Vanguard, Crucible, Dead Orbit, Future War Cult, New Monarchy, Crota's Bane, Queen's Wrath, House of Judgment, and Gunsmith)
 * Strike Hoard Chests
 * Weekly Nightfall Strike
 * Archon's Forge
 * Wrath of the Machine (Heroic)
 * Crucible legendary drops
 * Iron Banner
 * Trials of Osiris end-of-match and The Lighthouse rewards