I understand that Harry and his friends were morally opposed to using evil spells that would kill their enemies, but what baffles my mind is why didn't he snap his enemies' wands when he had the chance?
Specifically I'm talking about in Order of the Phoenix
when Harry and friends are battling the Death Eaters in the department of mysteries (chapter 35). Harry keeps stunning his enemies, making it an especially opportune time to take their wands and break them. I've ruled out the idea that the wand is hard to break since it happens to Neville in that very scene.