These are, without explanation, what applies when you are in your Mobile Suit. This narrows your abilities, and gives your Pilot a distinct fighting style as well, making him/her stand out, and fleshing them out to a greater extent. There are six different specialities in MS Saga: World at War.
Overall melee ability; how well you can handle a sword, claw, or other melee weapon.
See Melee Weapons for a full list of weapons.
How well your character can use beam weapons. This doesn't mean beam sabers since Close Range does that, but beam rifles and cannons would be affected by this.
See Beam Cannons, Beam Guns and Beam Rifles for affected weaponry.
Ah, the ever standard speed stat. This allows your pilot to push those thrusters to their limits, flying at top speeds. Transformable suits love this thing.
See Transformable Mobile Suits.
Another pretty standard stat, this will be your abilities to fight under sustained fire, and continue to fight damaged. It will also affect you MS's overall durability.
This one would apply to all those fancy doo-dads that can come with your MS. A Gouf's shock whip, or a Radar Jammer would be something for this stat. A stealth specialist should use this, just as an idea/example.