There is a twitch promotion allowing you to get Purple Footprints EffectPurple Footprints EffectBoots Modifier
Stack Size: 20Adds purple footprints to a pair of boots.Right click this item then left click some boots to apply it., Purple Weapon EffectPurple Weapon EffectWeapon Effect
Stack Size: 20Adds a Purple effect to a weapon.Right click this item then left click a weapon to apply it. and Purple Portal EffectPurple Portal EffectPortal ModificationThis character's portals use a purple effect.Right click this to set or remove your Portal effect. if you have twitch prime.
Projectile WeaknessCurse, Spell, AoE, Duration
Mana Cost: (24 to 50)
Cast Time: 0.50 secRequires Level 24Curses all targets in an area, making them easier to pierce and to knock back, and increasing the damage they take from projectiles.Per 1% Quality:
Cursed enemies take 0.5% increased Damage from ProjectilesBase duration is (9-10.9) seconds
Projectiles have an additional 50% chance to Pierce Cursed enemies
Hits on Cursed Enemies have an additional 25% chance to Knockback
Cursed enemies take (25-44)% increased Damage from Projectiles
(0-76)% increased Area of EffectPlace into an item socket of the right colour to gain this skill. Right click to remove from a socket.Acquisition
This wicked curse alters the very flesh of those afflicted, turning their armor and hide to mere paper. Any projectiles striking a cursed target have a high chance of piercing it, boring straight through to hit additional enemies standing behind. Foes under the Projectile Weakness curse will find themselves frustrated trying to reach the archer, since every volley has a good chance of causing a knockback. A Ranger trained in the curse of Projectile Weakness will be counted amongst the most feared combatants on the battlefield.Description on the official Path of Exile website 
Skill Functions and Interactions
- Cursed Enemies take #% increased Damage from Projectiles: because this modifier is an increase to the target's damage taken, it is multiplicative with players damage dealt and additive with any other increased damage taken effects on the target. It does not affect damage dealt by damage over time effects such as poison, ignite, or Essence DrainEssence DrainProjectile, Spell, Duration, Chaos
Mana Cost: (9 to 27)
Cast Time: 0.75 sec
Critical Strike Chance: 5.00%
Damage Effectiveness: 60%Requires Level 12Fires a projectile that applies a damage over time debuff when it hits. You are healed for a portion of the debuff damage. The debuff is spread by Contagion.Per 1% Quality:
1% increased Chaos DamageDeals (21.5-809) Base Chaos Damage per second
Regenerate 0.5% of Debuff Damage as Life
Base duration is 3.8 seconds
Deals (6-233) to (9-349) Chaos Damage
Modifiers to Spell Damage apply to this skill's Damage Over TimePlace into an item socket of the right colour to gain this skill. Right click to remove from a socket..
- Additional Pierce and Knockback Chance: any projectile type has a higher chance to pierce (additive with other sources of piercing chance) and a chance to cause the target to be knocked away from the player who created the projectile. It does not matter what direction the projectile strikes from, knockback is always away from the player who initiated the spell or attack projectile.
- Projectile Weakness can be turned into an aura by linking it with the Blasphemy SupportBlasphemy SupportSupport, Curse, Aura
Mana Reserved: 35%
Can store 1 use(s)
Cooldown Time: 0.50 secRequires Level 31Per 1% Quality:
0.5% increased Effect of Supported CursesSupported Curse Spells are Cast as Auras
(0-76)% increased Area of Effect of Curse SkillsThis is a Support Gem. It does not grant a bonus to your character, but to skills in sockets connected to it. Place into an item socket connected to a socket containing the Active Skill Gem you wish to augment. Right click to remove from a socket..
Gem level progression
Quest rewardThis skill is given as quest reward for the following quests:
|Lost in Love|
Vendor rewardThis skill can be bought at the listed npc vendors after completing the following quests:
|Lost in Love|
|A Fixture of Fate|
Related helmet enchantments
The following helmet enchantments affect Projectile Weakness:
|EnchantmentProjectileWeaknessCurseEffect1||66||20% increased Projectile Weakness Curse Effect|
|EnchantmentProjectileWeaknessCurseEffect2||75||30% increased Projectile Weakness Curse Effect|
|EnchantmentProjectileWeaknessDuration1||66||30% increased Projectile Weakness Duration|
|EnchantmentProjectileWeaknessDuration2_||75||45% increased Projectile Weakness Duration|
- "Dexterity skills". Official Path of Exile website.
- Mark_GGG (April 16, 2014). "Vulnerability Quality". Official Path of Exile Forums. Retrieved April 16, 2014.
- Mark_GGG (July 26, 2016). "Verify confused about projectile weakness double dipping with poison.". Reddit. Retrieved January 24, 2017.