Of course, there is the fact that Elijah is the polar opposite of David - David is unbreakable while Elijah is extremely breakable. Many superheroes and their villains are "opposites." To better emphasize that point, the first three times we see Elijah in the film, we see him in a glass reflection. Obviously, this is to signify his “breakable” condition.
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In the opening scene of the film in 1961, the first shot, we see the infant Elijah in the reflection of the dressing room mirror.
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The next time we see Elijah he is a 13 year-old child in 1974. We see his reflection in the television set.
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Finally, we see Elijah in the reflection of the vintage comic art piece in his store, “Limited Edition” as he describes the characteristics of the piece to a not so potential buyer.
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Elijah’s hair is big and combed funky to make his head appear as though it were proportionally larger than his body – something that Elijah himself states is a common characteristic among villains. His coats and wardrobe often make his body appear slender to accentuate this feature even more.
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Elijah's eyes. Just as his mother stated, villains are often depicted with larger than normal eyes. And Samuel L. Jackson has some big eyes in comparison to David’s.
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In a lot of scenes, when we are looking through Elijah's point of view, the camera sometimes gives us an upside down shot. It does this both times when Elijah has a comic book in his lap. And when he sees the man with the gun in the subway station. This could possibly represent Elijah's "skewed perspective on the world," as his mother stated.
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In the comic book store, Elijah knocks over the comic books THREE times, causing destruction to eventually find "the one" comic book that he needs. This could parallel to the THREE times he actually did cause destruction in the city to find "the one" person he was looking for. (A Stretch...I know.)
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His car. If that’s not a villain’s car, I don’t know what is. LOL

Just like many comic book archenemies, Mr. Glass knows all about Everyman, which makes him VERY dangerous, even though he's not a physical match to Everyman. Lex Luthor is very inferior to Superman, but he knows his weaknesses (kryptonite) and plays mind games with him. Bane knows all of Batman's secrets and used that to break him. The Green Goblin knows Spider-man's identity, and the second Green Goblin was even Spider-man's best friend before he turned evil. Magneto was good friends with Charles Xavier, so he knows all of his secrets and even how he thinks...the list goes on....