There are three varieties of Balder Knights: Side Sword, Rapier, and Crossbow. Those wielding rapiers are stronger and drop more souls. The Rapier variant of the Balder Knight can switch stances, holding its weapon at chest level, pointed at the player. While its stance is altered thus, the Balder Knight can parry.
Balder Knights have a fair amount of health, and are a considerable threat to new characters. Even one-on-one, they can be very dangerous. Any ranged attack is useful against them, but they are fast and will close the gap quickly. Firebombs can be very useful in defeating them. Critical attacks, such as the Parry and Riposte and Backstab, are exceedingly efficient methods to dispatch these enemies.