Skills
The first skill you’ll unlock for Cornelius is Spiral Claw. This allows him to perform a forward spin dash with the sword extended, and you can move up or down while using it. Spiral Claw will work well on groups of enemies, as you can quickly charge through them while dealing damage. This also allows you to get past them, dealing back damage. You can also use this skill against large bosses. Spiral Claw won’t allow you to get past bosses, but you can continuously deal damage to them by moving up or down while performing this skill. The continuous damage should let you stagger most bosses.
Whirling Blade is another great skill that Cornelius can use for crowd control. While it doesn’t work that well on bosses, it will let you clear out groups of enemies surrounding you. Cornelius can trap enemies in his whirlwind, and even move left and right to hit anyone who might be out of his reach.
If you’d prefer to use Cornelius’ magical skills, I recommend investing points into Spark Bolt and Plasma Circle. Spark Bolt is great for stunning regular enemies with an electric shot, and Plasma Circle will zone your foes by surrounding your body with multiple shots. Later on in the game, you’ll also unlock Mega Spark, which allows Cornelius to release a powerful, charged electric shot. I didn’t find his lightning magic to be very useful against bosses, but it is extremely handy when dealing with mobs.