“yet also true that humans can ultimately determine another’s harm or good,”
I have learned much about bechira and while I have learned that a person can chose to inflict harm on another person even if that person does not “deserve” it, I have never heard it said that a human can determine another’s harm or good. Human’s are only capable of doing, they have no control over the outcome.
regarding your glasses, as I thought I already stated, I have no problem accepting that everything is from Hashem and that people have bechira to harm.