Tell us about yourself!
This is incredible! One of the coolest cosplay weapons I've ever seen AND coolest "made real" sci-fi weapons I've seen. You deserve to win.
Real Laser Arm Cannon From Metroid!
I am almost certain it is a 5V regulator. He is using this because he essentially built his own arduino. If you use an arduino Nano like the diagram describes you wont need this. Also for anyone looking at my comment, I figured out my issue wasnt any mistake on my side at all it was a faulty XBEE chip.