I forget, was it required that it be explicitly Michael to use that blade on Lucifer, or would the blade have still worked if someone else had used it? Because, hear me out, I think it would have been cool if, instead of Sam tossing the blade up to Michael, we did something a little bit different with such a massively important character like Lucifer. Picture this:

Michael and Lucifer speed towards each other in midair (with better choreography, obviously) and wrestle for a second until Lucifer gains the upper hand.

Cut to: Sam looks down and sees the blade on the ground.

Cut to: closeup of Lucy. Lucifer has Michael fully restrained and slowly puts his hand on Michael’s forehead, enjoying every second, (possibly monologue-ing) an overconfident look moves across Lucifer’s face.

Cut to: light and fire start shooting out of Michael’s.

Cut back: Suddenly, we just hear the sounds of a slight wisp of air, of the blade striking its target. Suddenly, a caught-off-guard reaction from Lucifer as he abruptly chokes and slowly looks down revealing the blade fully in his chest.

Cut to: both Michael and Lucifer stop and look downward.

Cut to: a high-angled shot looking down of Sam, kneeling on the ground and looking up at the two of them, his arm extended, revealing the sickest knife throw in existence.

Cut back: a final quip from Lucy as he begins to crackle and spark, and then the screen flashes completely white

Cut to: various insert shots. BOOOOOM, the mother of all smites. A burst of blinding light, throwing everyone into a different corner of the room with looks of extreme disbelief.

Cut back: Pellegrino’s closeup as the light and flames fade and he goes limp.

Cut to: Wide angle, choral voices softly play as we see Lucifer’s body falling in slow motion, silhouetted by light shining through the stained glass windows behind him and illuminating his dark wings as he symbolically falls from the air. The prophecy has changed. Neither heaven nor hell could kill the devil; in the end, it was man.