My impression of Madame Ma of DGSD is that she was a slu-tty woman whose deadly power was her beauty coupled with her callous ability to manipulate men and tell lies. I never thought she was one who had the ability to kill directly with her own hands.
When Ah Chu (in the guise of Elder Bak of the Beggar's Union) went to visit her to learn the identity of Leader Big Brother, however, Madame Ma demonstrated the Deun Family's 1 Yeung Finger Technique to mislead Ah Chu and Kiu Fung into thinking that Leader Big Brother was Deun Jing Tsun.
I'm surprised that Madame Ma could wield the 1 Yeung Finger, although she obviously wasn't very powerful in this skill. Anybody who could wield this skill with any proficiency at all was no pushover. I thought Madame Ma had no martial arts ability whatsoever.
I'm also surprised that Deun Jing Tsun was so cavalier about teaching this skill to an outsider; during the time of DGSD, the 1 Yeung Finger Technique was supposed to have been restricted to the Deun Royal Family only. Despite being a philanderer, Deun Jing Tsun was, I thought, fairly responsible about his family's martial arts secrets.