A video recently posted on this site shows off a large amount of customization. I managed to take a few pictures of the abilities names and descriptions, unfortunately, it's in German. Is anyone here both willing and able to translate?
Economize T-ENG: prevents the automatic loss of thermal energy.

Defense 1: Increase the defense and reduce the offensive power.

Critical damage 1: better chance for a critical hit by reducing your defense.

Head Start: start a match with the maximum number of Gum Grenades.

Head Start: start a match with the maximum number of Plasma Grenades.

T-Eng weapon master 1: energy weapons only need a small amount of T-Eng.

VS Master 1: reduce the cost of T-Eng when controlling a VS and increase the repair speed.

Recovery 1: stronger effect for the Harmonizer in Campaign mode. Passive health regeneration in MP mode.

Silent: let you run silently so enemies will not be aware you.

Head Start (T-ENG): start a match with extra T-ENG, also when you respawn.

Invisible: invisible on enemy radar.

Rescuer: if T-Eng is zero, you wont lose your health.

Close combat 1: increase your close combat power.

Head Start (Ammo): start with maximum ammo for your standard weapon, also always when you respawn.

Head Start: start a match with the maximum number of Disc Grenades.

Quick Return: Shorter Respawn time and faster datapost activation.

Evade 1: lengthens the invincibility phase during a roll but increases the damage after this phase for a short time.

Special Cover I: saves you from some type of damage.

Firepower 2: a more powerful version of "Firepower I" Increases your attack power and your damage sensitivity (requires 2 ability slots).

Points 1: more career points.

VS Destroyer: improves the ability to hit the VS + increases the damage dealt to a VS on its weak points.

Sprinter I: sprint longer

EDIT: added the translations and a 22nd ability.