[ The wand is gone as soon as its work is done; what Severus calls 'an old dueling trick' is actually a spell of his own design, used to hide it over the summers he had to spend at home. ]

A focusing tool. [ Which he doesn't really like explaining, even to non-muggles. He's far from embarrassed, but he prefers to avoid outlining his practices too closely. It makes him feel vulnerable. ]

It would bleed if I stuck it with a needle, [ Severus says, obviously meaning the bird as he outstretches one hand and nudges the little thing with spindly fingers. It chirps and flutters and sidesteps, hopping. ] But the blood would vanish when the transfiguration reverted. Or before.