He mentions it in one line. "I recovered most of the fragments"He just put it back together like it was made of Legos.
He stabs Satan, pulls it out and Satan just falls on his face. He doesn't implode or disintegrate, just falls on his god damned face like he blacked out on Tequila.
Then Dracula revives Alucard, Alucard asks what happens next, Dracula looks at the Mirror of Fate, then smashes it. Followed by "Who knows what fate has in store?" before walking off into an alley.
The writers had no idea how to finish the story from the looks of it. Maybe they'll wrap it up in the dlc, but even that is shady as hell.
I should also mention that there was no post credits cutscene either. I let the entire credits play out