Early on in the game, there is a cut scene where you meet a character called "the Betrayer"
In that cut scene he has these lines of dialogue:
I told you all to leave me here. I am where I belong. Saving your people will not bring you peace... only make the burden you carry worse. And now you seek to defy the Khan Maykr herself. It is your people's time to give penance... just as it was mine. Hear me, Slayer - When his heart is laid to rest... then his soul will be at peace.
The Betrayer then takes out a small implement (looks a bit like some futuristic vape) and tosses it to the Doom Slayer.
What is this small implement?