LVL 10 +1 Double Stab(1)
LVL 11 +3 Double Stab(4)
LVL 12 +3 Double Stab(7)
LVL 13 +3 Double Stab(10)
LVL 14 +3 Save SP(3)
LVL 15 +3 Save SP(6)
LVL 16 +3 Save SP(9)
LVL 17 +3 Save SP(12)
LVL 18 +3 Save SP(15)
LVL 19 +3 Save SP(1 cool
LVL 20 +3 Save SP(21)

10 Double Stab
21 Saved SP

EXPLANATION: Double Stab is to be 10 for Triple stab. Dark Sight will not be need and instead saving SP because Triple stab can go to 10. Dark Sight will be maxed later and Nimble body is useless because they already have high avoidability.

2nd Job (20-Semi Dualer)

LVL 20 +10 Triple Stab(10), +5 Mastery(5), +6 Booster(6)
LVL 21 +3 Mastery(9)
LVL 22 +3 Mastery(12)
LVL 23 +2 Mastery(15)
LVL 24 +3 Mastery(1 cool
LVL 25 +2 Mastery(20), +1 Disorder(1)
LVL 26 +2 Disorder(3), +1 Dark Sight(1)
LVL 27 +3 Dark Sight(4)
LVL 28 +3 Dark Sight(7)
LVL 29 +3 Dark Sight(10)
LVL 30 +3 Dark Sight(13)

10 Triple Stab
19 Mastery
6 Booster
3 Disorder
13 Dark Sight

EXPLANATION: . Triple Stab is needed and is main attack till around level 50. So it is maxed. Mastery doesn't need to be 20 but can be 19, they have accuracy already so it doesn't need to be maxed. Mastery will be maxed later though. Booster is more helpful then you think, but will stay at level 6 which is a minute. Later Booster will be maxed and dark sight will be finished maxed later.

2nd Job+ (30-Dualer)

LVL 30 +1 Slash Storm (1)
LVL 31 +1 Final Blow(1), +2 Self Haste(2)
LVL 32 +3 Self Haste(5)
LVL 33 +3 Self Haste( cool
LVL 34 +3 Self Haste(11)
LVL 35 +3 Self Haste(14)
LVL 36 +3 Self Haste(17)
LVL 37 +2 Self Haste(20)
LVL 38 +3 Slash Storm(4)
LVL 39 +3 Slash Storm(7)
LVL 40 +3 Slash Storm(10)
LVL 41 +3 Slash Storm(13)
LVL 42 +3 Slash Storm(16)
LVL 43 +3 Slash Storm(19)
LVL 44 +1 Slash Storm(20), +2 Final Blow(3)
LVL 45 +3 Final Blow(6)
LVL 46 +3 Final Blow(9)
LVL 47 +3 Final Blow(12)
LVL 48 +3 Final Blow(15)
LVL 49 +3 Final Blow(1 cool
LVL 50 +2 Final Blow (20), +1 Dark Sight(14)
LVL 51 +3 Dark Sight(17)
LVL 52 +3 Dark Sight(20)
LVL 53 +3 Booster(9)
LVL 54 +3 Booster(12)
LVL 55 +3 Booster(15)

20 Slash Storm
20 Final Blow
20 Self Haste
20 Dark Sight
15 Booster

EXPLANATION: I would max haste early because it is helpful for going around maps and jumping around in CPQ. 1 Slash Storm helps you kill mobs in the beginning. Maxing Slash Storm will let you hit more monsters, while gaining range and damage. Final Blow is then maxed as a 1v1 attack. The extra SP maxes Dark Sight and booster. Final Blow later is replaced by Bloody Storm later. Booster is still finished in later builds.
3rd Job (55-Dual Master)

Build 1
LVL 56 +3 Flash Jump(3)
LVL 57 +3 Flash Jump(6)
LVL 58 +3 Flash Jump(9)
LVL 59 +3 Flash Jump(12)
LVL 60 +3 Flash Jump(15)
LVL 61 +3 Flash Jump(1 cool
LVL 62 +2 Flash Jump(20), + 1 Save SP (1)
LVL 63 +3 Save SP(4)
LVL 64 +3 Save SP(7)
LVL 65 +3 Save SP(10)
LVL 66 +3 Save SP(13)
LVL 67 +3 Save SP(16)
LVL 68 +3 Save SP(19)
LVL 69 +3 Save SP(22)

20 Flash Jump
22 Save SP

EXPLANATION: Flash Jumpt is fun to use and very helpful to travel with, especially with Haste already. Flash Bang and Tornado spin are kind of useless and not needed, because it is replaced by 4th job skills. So its not worth the SP.But they will still be maxed in next job because of extra SP.

3rd Job+ (70-Slasher)

LVL 70 +1 Mirror Image(1), +10 Bloody Storm(10), +15 Flying Assulter(15)
LVL 71 +3 Flying Assulter(1 cool
LVL 72 +2 Flying Assulter(20), +1 Owl Dead(1)
LVL 73 +3 Mirror Image(4)
LVL 74 +3 Mirror Image(7)
LVL 75 +3 Mirror Image(10)
LVL 76 +3 Mirror Image(13)
LVL 77 +3 Mirror Image(16)
LVL 78 +3 Mirror Image(19)
LVL 79 +1 Mirror Image(20), +2 Upper Stab(2)
LVL 80 +3 Upper Stab(5)
LVL 81 +3 Upper Stab( cool
LVL 82 +3 Upper Stab(11)
LVL 83 +3 Upper Stab(14)
LVL 84 +3 Upper Stab(17)
LVL 85 +3 Upper Stab(20)
LVL 86 +3 Owl Dead(4)
LVL 87 +3 Owl Dead(7)
LVL 88 +3 Owl Dead(10)
LVL 89 +3 Owl Dead(13)
LVL 90 +3 Owl Dead(16)
LVL 91 +3 Owl Dead(19)
LVL 92 +1 Owl Dead(20), +2 Tornado Spin(2)
LVL 93 +3 Tornado Spin(5)
LVL 94 +3 Tornado Spin( cool
LVL 95 +3 Tornado Spin(11)
LVL 96 +3 Tornado Spin(14)
LVL 97 +3 Tornado Spin(17)
LVL 98 +3 Tornado Spin(20)
LVL 99 +3 Advanced Dark Sight(3)
LVL 100 +3 Advanced Dark Sight(6)
LVL 101 +3 Advanced Dark Sight(9)
LVL 102 +3 Advanced Dark Sight(12)
LVL 103 +3 Advanced Dark Sight(15)
LVL 104 +3 Advanced Dark Sight(1 cool
LVL 105 +2 Advanced Dark Sight(20), +1 Booster(16)
LVL 106 +3 Booster(19)
LVL 107 +1 Booster(20), +2 Flash Bang(2)
LVL 108 +3 Flash Bang(5)
LVL 109 +3 Flash Bang( cool
LVL 110 +3 Flash Bang(11)
LVL 111 +3 Flash Bang(14)
LVL 112 +3 Flash Bang(17)
LVL 113 +3 Flash Bang(20)
LVL 114 ANY SKILL
LVL 115 ANY SKILL
LVL 116 ANY SKILL
LVL 117 ANY SKILL
LVL 118 ANY SKILL
LVL 119 ANY SKILL
LVL 120 ANY SKILL
i didnt make this, i found dis on http://www.gamekiller.net/maple-story-general/67798-maplestory-dual-blade-build-skill.html lol