The Dark Queen and I Strike Back

Suddenly transported to another world. I was called the "suitable one," he who could handle the world's strongest power, the "holy sword." I thought I would use that power to make a great impact in this new world. However, the world was such that humans were abusing "monsters" and "beasts." Questioning my own convictions, I ask, is this correct? Who should I use this power for? This is the beginning of an Isekai battle fantasy!