Buso Renkin 

An Alchemic weapon used to kill homuncului. It is what is created by the Kakugane. It is activated by the deppest part of the human sych. It mirrors the owners peronality.

In "Buso Renkin" Kazuki is given a kakugane. When it is activated it becomes a lance

Buso Renkin by Nightmare Yoshimori October 22, 2006