Here's the breakdown of why, despite being the true Master of the Elder Wand, Voldemort was still capable of killing with it:
* The Elder Wand's Allegiance is Complex: The Elder Wand's allegiance is not a simple "ownership" situation. It's more about respect and dominance.
* Voldemort's Belief: Voldemort believed he was the true Master of the Elder Wand because he had disarmed its previous owner, Harry Potter, and he believed this act gave him control.
* Harry's True Mastery: While Voldemort thought he was in control, the Elder Wand actually recognized Harry as its true Master. This was because Harry had defeated Draco Malfoy, who had disarmed Dumbledore, who had defeated Grindelwald, who had defeated the previous owner.
* The Importance of Intent: The Elder Wand is not a magical weapon that automatically chooses its side. It is influenced by the intent and will of its wielder. Voldemort's evil intent and desire to conquer led the Elder Wand to perform the spells he desired, despite its true allegiance.
Essentially, the Elder Wand's allegiance to Harry did not prevent Voldemort from wielding it effectively. It was Voldemort's own belief that he was the true master, coupled with his powerful magical abilities and intent, that allowed him to kill with the Elder Wand.
This also highlights a crucial theme in the series: True mastery is about more than just power, it's about understanding and respect. Harry's victory over Voldemort was not just about disarming him, but also about understanding the wand's true nature and showing respect for its history.