Not all Arms that you can customize your characters with are all the same shape and size. Each Arm has its very own elemental enhancement, as well as its individual type.
An Arm can be one of seven different elements: Fire (Burns & Knocks Down Targets), Electric (Temporarily Stuns & Lowers Defenses of Targets), Wind (Creates Knockback Effect), Ice (Stuns & Slows Down Targets), Stun (Freezes A Target In Place), Explosion (Creates Knockback Explosion), or Blind (Temporarily Blurs Target's Vision).
Any given Arm will also be one of five different types: Glove (Basic Standard Punching), Multi-Shot (Hits Targets Multiple Times), Curve (Standard Punching That Curves When Thrown), Heavy (Standard Punching That Deals Massive Damage), or Whip (Extends Across A Large Portion of the Battlefield).