Force Edge/Sparda

[Acedia]

First off, I'm pre-apologizing if this has been put up already. Or if there is a simple explanation.

Now here is the question...

To activate the actual sword "Sparda" it requires the two amulets given to Dante and Vergil.
As everyone knows, the amulets aren't even MENTIONED in DMC4.

How does Sanctus get Force Edge to transform into Sparda?

Another thing to mention, at the end of DMC1, when Dante and Trish bust down the door to hunt demons, Trish has "Sparda" on her back and Dante has "Force Edge" on his back.

Again, apologizes for being loopy, but can there be a few concentrated assumptions or answers to these questions?

 

[Hoskar.Angelo]

The Sparda never returned to the Force Edge form. Trish gave it to Sanctus already activated.

On the DMC1 ending, I guess Dante has Alastor on his back. Is hard to tell 'cause that two swords have very similar hilt, but seeing the Sparda on Trish' back, it may be Alastor.

 

[Acedia]

Right, got my Devil May Cry lore stuck in a bunch!
Thank you!

There's a Devil May Cry Wiki, that states Dante has Force Edge.
I've replayed the video quite a few times, and I have reason to believe that it is too.
It resembles Force Edge a lot more then the Alastor.
But, it is arguable.