Talk:Displace/@comment-44309297-20200530221234/@comment-16533050-20200530222147

She doesn't have the ability before the Outsider provides these items (similar to the initial missions in D1 and D2), hence the powers have to come from them.

In the corresponding articles it indicates that the Black Shard Arm draws and replenishes its power from the Void itself, allowing her to use Displace and Semblance, and provides the energy for Foresight. It is also able to interact with hollows.

Conversely, the Sliver of the Eye enables Billie to see things that were hidden to her before, such as the hollows, and enables her to use Foresight and Displace.

I take it to mean the Arm is basically the battery/power source and main device while the Eye (being part of a previous deity) is the focus allowing interaction that sends the power through.

This corresponds with how the Mark and the Outsider work in relation to the Void. The Void is the Power Source and it is stabilized by the Outsider. The Outsider then grants his Mark to individuals. The Mark via the conduit that is the Outsider is able to then tap into the power of the Void.

Ugh, sorry for the reply becoming so TL/DR. :(