The impact is a weak bonk from what's left of the arrowhead, as the burning pink magic has consumed most of the arrow's mass by this time. And on hitting him, said magic pours downward, covering his whole body in a bright pink glow. From the outside it looks like a brilliantly-shining pink silhouette, like a pokemon that's evolving--and indeed, that silhouette does change shape, shrinking downward and inward, hips flaring out and a long, slim tail sprouting out from the back, hair visibly growing longer while two big triangles rise out from the top of the head. To the changing boy this all feels like a very pleasant tingling, pushing and sometimes tugging all across his body, as his voice rises higher and higher~...! The changes to the silhouetted body end with a forward push from the chest, two very distinct bumps appearing from there, before the magic finally shatters off of the victim and disappears, leaving behind a
cute catgirl. Her clothes have changed to a sweater, bra, panties, a plaid skirt and long black leggings, and she finds a stick of tasty off-branded pocky in her mouth, the box for it in one hand and another stick in the remaining hand. Her attention is drawn immediately to a nearby boy with goggles on top of his head, her heart pounding and the heat of a blush rising in her cheeks as the pink magic's second effect, a targeted attraction/infatuation spell, takes hold.
(For that matter, any nearby bystanders will obviously have their attention drawn at least slightly to the sudden, flashy display of magic)