"Nightsticks," Pete said promptly. He put his drink down, again, and reached behind him to procure his wand from a hidden and secret location. "I will make you one."
He looked around, seeking something to transfigure with, and after a few moments of blank blinking, plucked a grass strand from his skirt and shook it out straight. A few muttered incantations had it shrinking and thickening, another had it turning black, and after a minute or two of furrowed brow, concerned squinting, and creative spell-casting, he had a muggle nightstick dangling from between his fingers.
"See?" he asked brightly, casting one final spell and handing it over to William. "It's regulation."