This is the work of Moussa, another involuntary guest at Abstergo, who is played by Michael K. Williams.
“I just hope he looks like a badass, basically,” Williams said, when asked what he hoped his costume will look like.
The little voodoo altar in the crafting area is, according to Williams, where Moussa keeps his “weapons.”
Though he admits that he’s “not a gamer” and had never even heard of Assassin’s Creed before being sought out for the role, Williams was extremely enthusiastic about his character(s) in the movie.