Only a few rooms before you have to fight the end boss, you encounter Cashias, the founder of the Knights of Cashias. It seems that his deeds while walking among the living were cruel enough to end up in Hell after he died.
While situated almost at the end of the game, Cashias can be easily tricked, making him a fairly easy boss.
Cashias will try to stay at a certain distance to the character; if you come to close, he will step backwards and he will step forward if you gain distance. He only uses one attack, a sword slash, to harm you.
This fight can be incredibly easy with the right items. He will treat the Summon Stone ghost like your character and since the ghost will always rush in like a madman, Cashias will be constantly pushed to the wall.
Because of his armor, he is completely immune to projectiles. But even this circumstance can be worked with; the poison cloud from Edea's Statuette doesn't count as a projectile, meaning that you can equip the item and shoot Cashias with fully charged paper seals or fireballs to completely destroy him with poison ticks.