Blue Eye Knights are likely the first major threat posed to new players of the game. They have more health, more varied attacks, and hit far harder than the other enemies in the area. There are two variants - one wields a Knight Sword and a Knight Shield, and the other uses a Claymore.
Three Blue Eye Knights are scattered around 1-1. Two of them are also found at the end of 1-2, just before the fog gate leading to the Tower Knight.
These enemies, particularly at the beginning of the game, require more care than any other enemies in 1-1 or 1-2, especially since the last two knights in 1-2 are capable of killing low-vitality players in a single hit.
The sword and shield users have a variety of attacks: a standard slash combo, a thrust attack, a guard break, and a massive slash indicated by a loud roar emitted by the knight, which does significantly more damage than any of its other moves. These variants are particularly susceptible to parrying, though it is not recommended to try this with the large slash, as the timing is difficult, and the attack does massive damage if it hits. One could also attempt to go for a backstab, which is easiest to do after the thrust, as it has longer ending lag.
The claymore wielder does a large amount of damage with every attack, but it moves and attacks slowly, and it is easily dodged. The best strategy is either to hit it and roll away, or go for a backstab - parrying is not recommended.
The two at the final corridor leading to the Tower Knight fog gate are best taken on one at a time, and with all other enemies dealt with. Parrying is riskier due to their immense damage output, so it may be wiser to block and circle around for a backstab.