EXPLAINING THE ARMS/BACKSTORY:
Toa Ihru was sent on a mission to stop the Mechbots, deadly robots that are being used to take over.
Ihru is in an abandoned warehouse, searching around when suddenly 50 Mechbots come up from behind. He jumps out of the warehouse, and they follow. He eventually ends up against the River of Energized Protodermis. He fights them, and thinks that he's winning, but the stealthy leader of the pack pushes him. Ihru falls into the River, but not before grabbing and taking the leader with him. The leader gets fused to Ihru's back, but Ihru is in control of both of them.
Basically robot gets fused to character's back, but character is in control of robot. Here are pictures of Mechbots and Ihru.
Ihru before being Fused: http://imgur.com/Uhhyxup