Becoming a Dual Blade
From the start-up screen click “Create new character” from that window on the upper right corner you will see Dual Blade next to the Adventurer choice. Click Dual Blade and create your character, and start the game. You will start off on Maple Island and at lv 10 go to Kerning City and talk to Dark Lord to become a Rogue.Becoming a Semi-Dualer
At lv 20 head to the new map in Kerning City (located in the hole in the bar where Dark Lord is).You will find your new job instructor, Sulhee. She will give you a quest to find a drop from oil lamps (I think, something like that.). To break them use the normal ‘Attack’ key. After you have obtained it return to Sulhee and she will advance you to Semi-Dualer.
Becoming a Dualer
At lv 29 you will receive a quest to kill Dark Lord resembling clones and receive a book after defeating them. They are rather easy to beat and have very little HP and deal very low damage.Return the scroll to Sulhee then at lv 30 go to Sulhee again and you will advance as a Dualer.
Becoming a Blade Specialist
When you reach lv 54 you will receive a quest from Sulhee, go to Arec (Thief 3rd job instructor in El Nath) and speak to him. Arec will bring up how you oppose the Dark Lord and you have to prove to him that DB are no longer trying to kill the Dark Lord, you'll have to kill White Fangs and collect their tails after you complete this he will give you a scroll as his recognition of the Dual Blade job. Once you hit level 55 return the scroll to Sulhee and you will advance as a Blade Specialist.Becoming a Blade Lord
Dual Blade's 3rd+ advancement is the same as all other adventurer's 3rd job advancement. Go to El Nath and talk to your 3rd job instructor, return to Vic and talk to Dark Lord. Fight Dark Lord clone. Return to El Nath, do your job question quiz, and advance. You're now a Blade Lord. Full instructions written belowDual Blade 3rd Job Advancement (Level 70)
Things to note:
Each dark crystal ore is around 200-250k (25/11/2010) on Izar server, so you will need 2mil mesos to buy 10 dark crystal ore and refine them into a dark crystal.
– Arec 
– Dark LordFirst talk to Arec in El Nath. Then, go back to Kerning and find the Dark Lord in the Jazz Bar. He will ask you to prove yourself by killing his clone. Get to Dangerous Swamp II through the sewers and click on the Dimensional Portal to enter the dungeon.
Dimensional PortalWhen inside, head towards of the right of the map and enter the portal. The next map will have the Dark Lord’s Clone. Kill him and receive a Black Charm
.
Dark Lord’s CloneHe will summon tauromacis so watch out, however he doesn’t deal much damage. Bring pots, but it should only take a few minutes to defeat him.
Bring back the Black Charm to the Dark Lord to get a Necklace of Strength 
, one of the items needed for the job advancement. Now head back to Arec in El Nath. Give the Necklace of Strength to Arec. Then she will ask you to get the Necklace of Wisdom from the Holy Stone. First make sure to get a Dark Crystal 
(or refined it using 10 dark crystal ore) for it will be needed to start answering questions. Then, go to Holy Ground at the Snowfield which can be accessed through Sharp Cliff II at the top right most door. There is no actual portal, press up near the door to enter.
, one of the items needed for the job advancement. Now head back to Arec in El Nath. Give the Necklace of Strength to Arec. Then she will ask you to get the Necklace of Wisdom from the Holy Stone. First make sure to get a Dark Crystal 
(or refined it using 10 dark crystal ore) for it will be needed to start answering questions. Then, go to Holy Ground at the Snowfield which can be accessed through Sharp Cliff II at the top right most door. There is no actual portal, press up near the door to enter.
Inside, go to the bottom and there are no monsters so don’t worry about dying. Talk to the Holy Stone.
It will ask you to use your dark crystal to try to answer the questions. Give it the dark crystal and answer the 5 questions. I would not try to answer them myself for if you get one wrong, you must get another dark crystal and start over. I suggest you going over to sea.hidden-street.net to check for the answers using the search box. Its better to sit down on a chair before clicking the stone.
If you get all the answers correct, you will be given the Necklace of Wisdom
. Go back to Arec and give her the necklace to receive the 3rd job advancement, Slasher! Congrats!Becoming a Dual Blade
Dual Blade's 4th job advancement is exactly the same as a normal adventurer. To be edited next time.
Credits - http://maplesushi.wordpress.com/
http://www.basilmarket.com/MapleStory-Guide-Ultimate-Dual-Blade-guide-314.html
Me for editing.
