Don’t put your wand there, boy! ... Better wizards than you have lost buttocks, you know!

Wands are only as powerful as the wizards who use them. Some wizards just like to boast that theirs are bigger and better than other people's.

But people only die in proper duels, you know, with real wizards. The most you and Malfoy’ll be able to do is send sparks at each other. Neither of you knows enough magic to do any real damage. I bet he expected you to refuse, anyway.”
“And what if I wave my wand and nothing happens?”
“Throw it away and punch him on the nose,” Ron suggested.

The Death Eaters can't all be pure-blood, there aren't enough pure-blood wizards left," said Hermione stubbornly. "I expect most of them are half-bloods pretending to be pure. It's only Muggle-borns they hate, they'd be quite happy to let you and Ron join up"
"There is no way they'd let me be a Death Eater!" said Ron indignantly...."My whole family are blood traitors! That's as bad as Muggle-borns to Death Eaters!"
"And they'd love to have me," said Harry sarcastically. "We'd be best pals if they didn't keep trying to do me in.

Apparently wizards poke their noses in everywhere!

Don't put your wand there, boy! What if it ignited? Better wizards than you have lost buttocks, you know."
"Who d'you know who's lost a buttock?"
"Never you mind...