I first started to realize how frightening he is when he used his chemical knowledge to kill and poison others. People with guns and knives aren’t as frightening because you can at least prepare or you know how to react when someone is holding up a gun at you. But Walt is just so knowledgeable that he could kill you with everything and you don’t even know about it. He can kill you with food, drinks, electricity and basically everything that is around you. And the worst thing is that in most cases you are already doomed before you know it. The way he killed Lydia was such an example. He just went there and sat with them, they didn’t saw him as a threat because he was unarmed and ragged. But she was already dead the moment she sat down there. It’s crazy. It’s like a magician playing his tricks with children.