Harry Potter and The Deathly Hallows - Not So "Unbeatable" Wand
In "Deathly Hallows", the elder wand is supposed to always win duels for its owner... So:
1) how did Dumbledore win the duel against Grindelwald in order to take possession of the wand?
2) Why when Dumbledoe and Voldemort were duelling in the ministry of magic in Order of the Phoenix, did Dumbledore NOT defeat Voldemort?
Deathly hallows, any edition