"Single drop of red" (Wuxia)
The term 一點紅 you are referring to is an assassin/ swordsman called '中原一點紅' in a Chinese Martial art novel 《楚留香》 by 古龍.
His signature move is a sword-thrust so precise that it only leaves behind a tiny wound, looks like a red dot on his opponent's forehead.
We don't know his true name. He was only known as '中原一點紅' in the novel
It is fictional, not a real martial art term
Notices:

In general, 一點紅 means 'the only female among a group of males'. It came from the Chinese expression '萬綠叢中一點紅' (a single red dot in a greenfield). Example: &quot;麗莎是我們出版社的一點紅&quot; means &quot;Lisa is the one red dot (only female member) in our publishing house&quot;

And 萬綠叢中一點紅 came from the poem 《咏石榴花》. (a poem about pomegranate flower) by 王安石（1021-12-18 ～ 1086-5-21）

今朝五月正清和，榴花詩句入禪那。


濃綠萬枝紅一點，動人春色不須多。


紅一點 refers to a single pomegranate flower among trees full of green leaves, a sign of early spring.


一點紅 is also the name of a plant that is used in traditional Chinese medicine