Knights are Warrior NPCs with 480 Health and 80 Armor (+20 vs physical attacks) with a self-heal in the form of Healing Signet. In every GvG battle, two Knights stand near the Guild Lord deep inside the both teams' Guild Halls. Contrary to other NPCs in GvG, Knights are very easy to aggro and lured out of position for relatively easy kills. However, they dish out a fair amount of pressure through degeneration and conditions, and can take down an unsuspecting target. In terms of their skill set, they are but the improved version of a Footman.
As a general rule of thumb, they will use Healing Signet when their Health drops to around 25%.