You fight him inside the Frozen Grotto. This second boss can be quite difficult because you will have to get arguably lucky with where he teleports.
-Nosferatu teleports around the room at random locations. Quickly notice where he appears and run up to him and attack with your sword.
-Every now and then he will summon two bats that fly in a circular pattern and close in on you. You can choose not to pay attention to them, but if you're low on HP and on MP for recovery, it might be best to run away from them and wait for a chance to attack Nosferatu.
-My favorite strategy is to use normal attacks only. You can easily get 5-7 hits on Nosferatu when he takes time to summon his pet bats. Using this strategy, it is possible to beat him under a minute.