Neji's uncle

[nite]

In the early chunin exams, Neji's uncle detected Killing intent from his brother.

so Why was he not used to help fight zetsu's ?

[Nara Yako]

perhaps the seal on the branch family alerts the head family of violent intents only

[Dracule]

What? Hizashi(Neji's father) was dead during the Chunnin exams so how could Hiashi (Neji's uncle) detect anything from him lol
And right now, Hiashi is still fighting Hizashi in the war.

[alexsimpson]

i think tht all ninja can sence killer intent because kakashi senced garra when he was spying on sasuke when they were training also
sasuke was paralised by orochimarus killer intent in the forest of death

[Alphonse Elric]

Either the seal or else he saw him activate his byukaugan outta nowhere and look at hinata gave it away. I doubt it's a ability.

[nite]

What? Hizashi(Neji's father) was dead during the Chunnin exams so how could Hiashi (Neji's uncle) detect anything from him lol
And right now, Hiashi is still fighting Hizashi in the war.

The flash back mate .

[DhattUchiha]

yea it's probably just from the juinjutsu

[Ira]

Hiashi can detect the intent only one at a time or only within his range at the most. Not in the whole battle ground where there are hundreds of Zetsus to weed out within limited period.

He may not be even available and already over worked due to his earlier fight though if he wasn't it wouldn't change the over all situation much because of above stated limitations.

[Sunzi]

He probably saw Hizashi's Byakugan activate that's always been my general understanding. I've always wanted to see the two fight however, without the Branch family seal holding back Hizashi.

[D3A]

Nejis dad was slowly activating his byakugan, Hinatas Dad noticed and murdered more of Neji's Dad's braincells than alcohol ever could

[Ira]

He probably saw Hizashi's Byakugan activate that's always been my general understanding. I've always wanted to see the two fight however, without the Branch family seal holding back Hizashi.

it's not just that- Bayakugan is said to have a great insight- better than sharingan. The main branch can see very fine chakra points etc. they can detect even slight changes in the flow and thus can sense emotions, heart rate, pulse those kind of things and interpret it..