His wand works well for her – if well means that she doesn't blow anything up. It feels friendly enough to her hand, but is weak – the charms she tries only work about half the time, and when they do work, they are pitiful compared to what she could accomplish with her own wand. But several numbing charms later she is left staring at his back with her hands fisted at her hips, biting the tip of her tongue lightly and wishing she had taken the time to learn some kind of cleansing charm – complicated spells – rather than having lazily relied on her ability to always have Muggle antiseptics on hand. It's too late now though.