From your own link:

“Although Schaft's supposed final words became famous, they were never confirmed. A Dutch World War II historian said a search through the Dutch archives does not ever mention Schaft saying "I shoot better!" During a post-war interrogation, Kuiper said he had been talking to Schaft when he suddenly heard a gunshot after which she cried out in pain and started shaking. Realizing that Schmitz had only grazed her, Kuiper took out his submachine gun and fired a burst at Schaft, after which she immediately collapsed. One of the shots hit her in the head, killing her.[12] It was the Dutch novelist Theun de Vries who added Hannie Schaft's last words as a poetic license in his book The Girl With the Red Hair (Het meisje met het rode haar, 1956)”