Dual Blade

The Dual Blade is an Emblem Heartless that is found in Kingdom Hearts 358/2 Days. It is one of the bosses at Halloween Town.

Kingdom Hearts 358/2 Days
This large and aggressive knight Heartless's skillful defense makes it tough to finish off. Though its focused slash can be stopped with a block, blasting the knight with Thundaga while it is storing up energy will stagger it, opening it up to extra damage, especially from magic.

Strategy
When facing Dual Blades and other Heartless in their family, the usual strategy is to circle around it and wait until their spin/thrust attack, then attack while it recovers. However, this knight has a much shorter recovery time than all the other knights, so hit it with Thunder magic to pause it for longer. As usual, ignore the sidekicks, since they tend to be replaced as soon as they are defeated. Instead, avoid/block their attacks and focus on taking out the boss first, and then go back and finish them one by one until they stop popping up. When it starts charging up for its rush attack, be sure to guard at the right time to knock it down and deal a painful combo while its down.

All of the "blades" have a similar attack pattern. When your physical attack is blocked, that is the time to cover. When it jumps up, air dash or glide around until it falls, avoiding its shockwave.