As in what part (or parts) of a character that are terrifying in action or given thought. It can be looks, personality, ideology, and/or an ability if applied with real-life implications.
For instance, Doomfist is scary because of his ideology; the concept of using conflict to further humanity implies a never-ending wave of war where if you aren’t strong, you will suffer or die.
They aren’t magic, but made of hardlight from their tattoes. Only the strongest can afford to use these, Genji doesn’t have them, his dragon comes from the sword