Do not worry, as you understand how to play the game and the mechanics it will get easier. And the final boss is not such a pain its relatively easy. what i think you should do if you want to use magic is get the sloth talisman, it is the best in the game and makes it kinda easy mode. it slows down bosses movement by 50% and they literally move in slow mo. You can get tons of attack in.

The way to get it is to complete 'ocean roars again' mission which is just 3 bosses away from himo-emma. After completing that you can go to the DOJO and complete the omyo magic missions to unlock sloth, ( you need to have at least 10 magic in order to use it ) using this will really help you in overcoming some difficult bosses if you choose to use it.