Why A Defender/Guard
The Defender/Guardian is the ultimate crowd control class, both in PvE and PvP. No other class has the potential to control and dictate incoming damage. Your role, put simply, is to do everything you can to make all of the damage to your party. Efficient parties and coordinated PvP strikes all rely on other members to do their job uninterrupted, whether it be casters to use their spells or melee types to get in and damage without getting hit. Efficient parties is also about taking on as many enemies as possible at a time without dying. You have, at your disposal, all the tools required to make this happen.
Enormous passive defense. Even without allocating your stats, you have more defense and HP than any other class does.
You are capable of taking much more damage and surviving.
An entire arsenal of debuffs. Everything you need to halt incoming damage from stun skills, skills that drop enemy attack power, skills that prevent casting, slow nets, and almost anything else you can think of.
Invincibility buffs. This is what makes Defenders/Guardians better at tanking than any other class. You have buffs that make you completely immune to incoming damage and even a couple of skills that reflect damage back to your opponent.
Provocation skills. To bring all of it together, you have a set of skills designed so that with all of your other tools, opponents are attacking you and not your party.
Defender/Guardian is a party class. If you prefer to solo, you’ll have fewer headaches as a Fighter/Warrior. That being said, you benefit your party most by putting every single point you get when you level up into Rec. This maximizes your ability to hold mobs on you and your survivability. You won’t need Str or Dex or anything like that. Let your party kill the mobs. You just focus on tanking them.
Party with Mages/Pagans. They are the greatest at dealing damage to multiple enemies at the same time. This is exactly what you’re looking for because your job is to tank as many enemies as possible at a time. Avoid partying Rangers/Assassins and Archers/Hunters. They specialize in taking down targets one at a time and are better off on their own. It is also a good idea to bring a healer for more difficult enemies and for nasty debuffs or poisons.
The Defender/Guardian is a preferred class in pvp, whether they choose tank class or battle class, with skills that make them very desirable classes to have as allies.