The Charge Beam allows you to increase the damage and effectiveness of the Arm Cannon.
The Charge Beam has a limited 'tractor beam' capacity. Use it to pull small objects to you.
There are Charge Combo enhancements scattered throughout the environment. They use the Charge Beam and the Missile Launcher in tandem to fire more effective blasts.
The Charge Beam increases the performance of each Arm Cannon mode.