I made a new list of where to enchant your skills, seeing as how the old list that's stickied has a huge amount of incorrect info. I checked all these myself and will be adding more detailed information for enchanting skills later, but so far this is what I made.
Town of Aden
Phoenix Knight
NPC Master Aiken
Location Warrior Guild
Eva’s Templar
NPC Master Sinden
Location Warrior Guild
Sword Muse
NPC Master Sinden
Location Warrior Guild
Duelist
NPC Master Aiken
Location Warrior Guild
Dreadnought
NPC Master Aiken
Location Warrior Guild
Hell Knight
NPC Master Aiken
Location Warrior Guild
Rune Township
Grand Khavatari
NPC Prefect Tazki
Location Warrior Guild
Titan
NPC Prefect Tazki
Location Warrior Guild
Dominator
NPC Seer Mekara
Location Mystic Guild
Doom Cryer
NPC Seer Mekara
Location Mystic Guild
Fortune Seeker
NPC Warehouse Freightman Daisy
Location Warehouse
Maestro
NPC Warehouse Freightman Daisy
Location Warehouse
Hunter’s Village
Adventurer
NPC Master Aren Athebalt
Location Warrior Guild
Wind Rider
NPC Master Stedmiel
Location Warrior Guild
Sagittarius
NPC Master Aren Athebalt
Location Warrior Guild
Moonlight Sentinel
NPC Master Stedmiel
Location Warrior Guild
Town of Oren
Cardinal
NPC Priest Vadin
Location The Einhasad Temple
Hierophant
NPC Priest Vadin
Location The Einhasad Temple
Eva’s Saint
NPC Priest Egnos
Location The Einhasad Temple
Ivory Tower
Archmage
NPC Magister Marina
Location 1st Floor
Mystic Muse
NPC Magister Joan
Location 2nd Floor
Storm Screamer
NPC Magister Ladd
Location 3rd Floor
Soultaker
NPC Magister Marina
Location 1st Floor
Arcana Lord
NPC Magister Marina
Location 1st Floor
Elemental Master
NPC Magister Joan
Location 2nd Floor
Spectral Master
NPC Magister Ladd
Location 3rd Floor
Hardin’s Academy
Ghost Hunter
NPC Dark Knight Mordred
Location Hardin’s Private Academy
Ghost Sentinel
NPC Dark Knight Mordred
Location Hardin’s Private Academy
Spectral Dancer
NPC Dark Knight Mordred
Location Hardin’s Private Academy
Shillien Templar
NPC Dark Knight Mordred
Location Hardin’s Private Academy
Shillien Saint
NPC Magister Anastia
Location Hardin’s Private Academy
Town of Aden
Phoenix Knight
NPC Master Aiken
Location Warrior Guild
Eva’s Templar
NPC Master Sinden
Location Warrior Guild
Sword Muse
NPC Master Sinden
Location Warrior Guild
Duelist
NPC Master Aiken
Location Warrior Guild
Dreadnought
NPC Master Aiken
Location Warrior Guild
Hell Knight
NPC Master Aiken
Location Warrior Guild
Rune Township
Grand Khavatari
NPC Prefect Tazki
Location Warrior Guild
Titan
NPC Prefect Tazki
Location Warrior Guild
Dominator
NPC Seer Mekara
Location Mystic Guild
Doom Cryer
NPC Seer Mekara
Location Mystic Guild
Fortune Seeker
NPC Warehouse Freightman Daisy
Location Warehouse
Maestro
NPC Warehouse Freightman Daisy
Location Warehouse
Hunter’s Village
Adventurer
NPC Master Aren Athebalt
Location Warrior Guild
Wind Rider
NPC Master Stedmiel
Location Warrior Guild
Sagittarius
NPC Master Aren Athebalt
Location Warrior Guild
Moonlight Sentinel
NPC Master Stedmiel
Location Warrior Guild
Town of Oren
Cardinal
NPC Priest Vadin
Location The Einhasad Temple
Hierophant
NPC Priest Vadin
Location The Einhasad Temple
Eva’s Saint
NPC Priest Egnos
Location The Einhasad Temple
Ivory Tower
Archmage
NPC Magister Marina
Location 1st Floor
Mystic Muse
NPC Magister Joan
Location 2nd Floor
Storm Screamer
NPC Magister Ladd
Location 3rd Floor
Soultaker
NPC Magister Marina
Location 1st Floor
Arcana Lord
NPC Magister Marina
Location 1st Floor
Elemental Master
NPC Magister Joan
Location 2nd Floor
Spectral Master
NPC Magister Ladd
Location 3rd Floor
Hardin’s Academy
Ghost Hunter
NPC Dark Knight Mordred
Location Hardin’s Private Academy
Ghost Sentinel
NPC Dark Knight Mordred
Location Hardin’s Private Academy
Spectral Dancer
NPC Dark Knight Mordred
Location Hardin’s Private Academy
Shillien Templar
NPC Dark Knight Mordred
Location Hardin’s Private Academy
Shillien Saint
NPC Magister Anastia
Location Hardin’s Private Academy