Being empowered by Malice and Will lets Johnny manipulate those forms of energy to however he wants. He usually uses this to channel it into his knife, acting as a lightsaber. He can use this to transform into his Awaker form, further boosting his stats, and comes with a double-bladed lightsaber.
Malice has its own world/realm. When it influences people or creatures, it drives them insane and corrupt, eventually turning them into monsters. People with this power can use it as magic, like channeling it into weapons, firing energy blasts, opening dimensional portals, summoning monsters, healing and resurrecting people.
Will is the counterpart or antithesis of Malice that can be used to repel, negate and cleanse any power of Malice. Johnny needed this to get complete control over his Awaker form.
Johnny at his strongest is universe level and mftl+. The description of his Awaker form has the power to destroy the world, and his sister Lady almost succeeded in destroying the world.
Awaker can do this shit.
The franchise does make a distinction between world and planet as Johnny’s ultimate weapon Cherry Bowie a short sword with enough strength to cut through the planet.
Johnny’s party member Shania's strongest Fusion form Tirawa, the sun spirit can call down solar flares from the sun.
His other party member is a Brazilian ninja Frank who gets a legendary sword Zondeek that was created at the same time as the world and can cut the Earth in half.
His vampire party member Hilda defeated her brother Joachim, a party member from Shadow Hearts 2, who created a pocket dimension containing countless stars inside his Sushi Restaurant.
Both of them can yeet people or monsters into space.
Joachim’s party fought against gods that can move quadrillion times the speed of light, and destroy worlds with a stray thought.
This would all be in character, Johnny’s job is to resolve problems, survive, and hopefully get the best ending. He replaces Touma as in he takes his spot as a student, resident, etc.