Awareness

Awareness is a perk in Fallout, Fallout 2, Fallout 4 and Fallout Tactics. It is also a skill that was to appear in the canceled Fallout: Brotherhood of Steel 2, where skills in this game work like perks do in other Fallout games.

Fallout, Fallout 2, and Fallout Tactics
Shows the HP, equipped weapon, ammunition type, and ammunition count of any characters, creatures, and robots when examining them.

Fallout 4
While this will reveal resistances for an enemy (in addition to a crossed-out symbol for immunities), it will not display any special characteristics. The main example of this is that ghouls are listed as having 1000 radiation resistance, when in truth they have a special effect that lets radiation damage heal them, making the resistance moot.

This is said to prove useful in detecting synths among your settlers, but it is useless. This myth probably originated from the Art (human) vs Art (synth) random encounter, in which the synth has higher damage resistance.

Also, while previous versions of Awareness (and for Fallout: New Vegas, the similar Living Anatomy) also revealed the enemy's health, Fallout 4's version only reveals the enemy's level, which can sort of be used to approximate how tough the enemy is.

Fallout: Brotherhood of Steel 2
The player character acquires the strange ability of making creatures temporarily turn away from them, although done so with varying % of success.