Killing Blow During the first, second and third battle rounds, ranged weapons equipped by T’au Empire models from your army have the [ASSAULT] ability. During the first, second and third battle rounds, while a unit is a Guided unit (see For the Greater Good), its ranged weapons have the [LETHAL HITS] ability.
Assault Weapons with [ASSAULT] in their profile are known as Assault weapons. If a unit that Advanced this turn contains any models equipped with Assault weapons, it is still eligible to shoot in this turn’s Shooting phase. When such a unit is selected to shoot, you can only resolve attacks using Assault weapons its models are equipped with.