No...that Ben sensed that zam wanted to kill him! The emotion. The intention. The whatever you want to call it. The fact that she was going to kill him, was thinking about it, and thats what he sensed. The fact it was on her mind. The same way Jedi can sense anger in each other (easy way to tell dark side from light side) they can sense it in non jedi!!
Although i've explained this twice before your choosing to read over it, please pay attention, repeating myself a fourth time really will be irritating.
how can you sense something that has no force in it? its not a naturally occuring thing. Notice when explaining the force to Luke, yoda said it was BETWEEN the land and the ship, not in the ship. "LIFE creates it". They can sense life, not objects. They can move objects, but they can't sense them. That's why a jedi can sense a person's next move and react faster. It has nothing to do with whether or not they have a gun, a knife, or just their fists.
Think of the force as an infra red camera. Humans and living creatures often show up as huge blasts of color and easily scene, bland inanimate objects, no life, show up as nothing, and cant be seen, or just appear as a blank outline in the surroundings.
I know in various situations you can see weapons in infra red but im using this metaphorically.