HwaRang:
One of the "Nobles" warrior in Shin-La kingdom in Korea. One of the elite warriors. They were basically "perfections" back then. Good at horseriding, bow, spear, sword, music and etc. Basically lady's man and a pimp back in the day or you can call them "Knights" in Korean version with musical side.
Class: Bow Class C, at "BulGokSa" dungeon, lvl 112
Skill 1: Reduces Musician's Physical Attack and Seals Musician Main and Merc's Magic (like mana seal effect)
Skill 2: Increases all Range Mercs Physical Attack AND chances of multiple hits (like Brutal will/seth) <-- I heard that this is a passive! Not too sure though
Skill 3: Sacrifice himself to increase ALL mercenary's Physical Attack
Maniac:
This Merc is from North America, Dr. Frankenstein! Go figure
Class: PowerSaw Class ?
Skill 1: Reduces all bow physical damages (sorta like Princess's) AND prevents all bow mercenary to use spells (like mana seal effect)
Skill 2: AOE spell (I think this is the same one as Maniac Main)
Skill 3: Awake 1 mercenary (haha like Stimulant potion!)
Musician:
This Merc is an European Violinist. In history, this is an actual guy but they made him as a female Merc.
Class: Musician Class ? Recruitment lvl 100 (this lvl info is from new KAO patch. Not from that link above)
Skill 1: Reduces PowerSaw Physical Damages and Prevents All PowerSaw Mercs to use spells (like Mana seal effect)
Skill 2: Removes "debuffs" for your mercenaries in "Columns" NOT ROWs! <-- so Imagine removing 1 iceridge/freeze/silence and mana seal on Monk. or imagine removing warcry in column! No need to holy guard! Apparently this magic semi-heals as well (from new KAO patch info)
Skill 3: I think this one is Melody of Madness