Class Guide ~ Bard

Damage & Heal build

Music Theory: 15 (Each Lv, Cast SPD +1%)
Lyrics & Poetry: 15 (Each Lv, G-Healing +1%)
Guitar Tuning: 10 (Each Lv, P-ATK & M-ATK +1 % when equip with a guitar)

Critical build

Music Theory: 15 (Each Lv, Cast SPD +1%)
Musical Knowledge: 13 (Each Lv, M-Crit Rate +1 %)
Folklore: 12 (Each Lv, M-Crit DMG +2%)

Pure buffer build

Music Theory: 20 (Each Lv, Cast SPD +1%)
Soothing Chords: 1 (Each Lv, Music of Life, HP Regen +10% per second & duration +2 seconds. Requires 10 music theory)
Lyrics & Poetry: 1 (Each Lv, G-Healing+1%)
Moody Style: 7 (Each Lv, Song of Illusion's duration +1 second. Requires 20 knowledge points)
Pop Style: 7 (Musical Encouragement's duration -1 second. Requires 30 knowledge points)
Solemn Music: 1 (Each Lv, Holy Concerto, G&P-Healing bonuses +20%, duration +2 seconds. Requires 35 knowledge points)

Damage & Buff build

Music Theory: 20 (EachLv, Cast SPD +1%)
Guitar Tuning: 10 (Each Lv, P-ATK & M-ATK +1 % when equip with a guitar)
Heavy Metal: 1 (Each Lv, Burning Metal, Fire DMG p/s and DEF penalty + 10%. Requires 15 knowledge points, guitar tunning 10)
Moody Style: 4 (Each Lv, Song of Illusion's duration +1 second. Requires 20 knowledge points)
Pop Style: 4 (Musical Encouragement's duration +1 second. Requires 30 knowledge points)
Solemn Music: 1 (Each Lv, Holy Concerto, G&P-Healing bonuses +20%, duration +2 seconds. Requires 35 knowledge points)

~ I hope it will be useful!