Bladers are dual sword wielders that are focused on maximizing physical abilities and use destructive skills that will kill an opponent instantly in the blink of an eye! Their build is focused on either Strength, to do more damage and gain more HP, or Dexterity to improve Attack, Attack Rate, Defense Rate and Evasion. Basically, Bladers depend mostly on their attack power and agility which are very effective in Player versus Player (PvP) or Player versus Environment (PvE).
Player vs. Environment (PvE)
Bladers are excellent for Player vs. Environment (PvE). They have very little defensive ability but is equally compensated by a higher evasion rate as their main defense. One of the amazing things in this class is that they have lots of skills that damage multiple targets. This makes them more invulnerable in Dungeons and other solo quests. Other than that, this class has lots of Knockdown/Knock-back skills that will interfere with some attacks from monsters. This is basically the best solo class in the game.
Player vs. Player (PvP)
There are lots of misleading ideas regarding Bladers when it comes to Player versus Player (PvP). Yes, Bladers have weak defensive abilities that give them the disadvantage of absorbing physical damage that gets through. But the key to winning a fight against another player with a Blader is to close in and kill him as quickly as possible. And since you have high Defense Rate and Evasion, you are somewhat untouchable during a fight. You also have Dash and Fade Skills that will help you avoid skill combos of other players. In skilled PvP, defense rate is better than defense, because it prevents knockdowns and other negative statuses, as well as damage, while defense only reduces raw damage. Iron Skin and Aura Barrier are now Passive Buffs. These buffs which became passive have now made the class almost like a tank with a considerably higher HP and defense all throughout your gameplay.
As for everyone's benefit, I have made a video on the skills of Blader starting from Novice - Master skills. Also, I have provided some combo samples that I currently use: