Mission 54: Eliminate the Dual Blade
A Dual Blade has surfaced in Halloween Town. Team up with Demyx, find it, and eliminate it at once.
Roxas tackles the Dual Blade in Halloween Town.
Before accepting the mission, equip a lot of Thunder magic to deal with the boss in a more effective manner. If you want to speed the process up, come back later with Thundara and Thundaga magic. Move to the right of the starting point and jump to grab the Unity Badge. Then follow the path straight defeating Heartless and unlocking a chest to obtain a Gust Shard. Once you reach the town square, the Dual Blade will instantly charge at you. Either defeat the Dual Blade, then search the area for treasures or vice-versa. Glide over top of the well to obtain the Ordeal Badge, then continue straight to reach the Ordeal Blazon. To the right of the Ordeal Blazon (hidden behind the wall) you will find a chest containing an Aerial Recovery LV+(L). After you have cleared the area, its time to RTC.
As time is tight on this mission and you can't use attack magic, you will need a Keyblade that can do heavier damage as long as it is one that does not have too many combo attacks. Don't stop attacking unless if it is preparing its charge attack, then block it with Guard, and attack it for heavier while it is knocked down. Though not completely recommended, any aid from the Pumpkin bomb and their explosive fire damage can help.
Long range magical combat is your only choice here. Equipping Crown of Guilt++ (though you do not need to install Magic Units in the gear slots) along with plenty of casts for Fire (or Fira) and Thundaga at LV. 5. Keep an eye on your surrounding enemies and carefully defeat the Skater Bombs with either regular attacks or Fire at long range to avoid getting caught up in the explosion from killing it. For Dual Blade, just avoid getting hit and wait until it charges up its charge attack so you can block it and then defeat it with Fire magic or Thundaga as it will receive more damage when knocked down. Just remember you are only allowed one mistake before your first sigil is lost.