Knights are heavily trained through the Prontera Knights’ strict education and strongly values rules and principles.They know how to handle ‘auras’ skillfully through systematic battle training and also can use their shields as a battle skill.
In order to change your job to a Knight at Level 25, look for High Knight Reord in Prontera.
He will give you a quest to protect someone at south of Prontera. This one is pretty easy, just attack this monster as usual, no strategy is really needed.
After finish you need to talk again to Knight job quest
In a Party
Most party(s) recruit and consider Knights as tankers.
Knights utilize their skills such as; Aura Shield & Provoke, combined with their high defense ratings (Mainly from heavy Equipments and Armour) that make the Knight a perfect tanker. They are able to take a lot of damage, and with their skills; able to draw mob attention away from party members and onto themselves, increasing aggro up to 300%.