Unlock the following abilities by getting the corresponding numbers of points by completing challenges. To choose an ability, press Square at the weapon selection screen:

ABILITY - POINTS
Carry three grenades - 20 points
Carry three syringes - 60 points
Placement C4 twice as fast - 100 points
Carry three smoke grenades - 140 points
Trip mines disarmed twice as fast - 180 points
Carry four pressure mines - 220 points
Close combat damage doubled - 260 points
50% more health - 300 points
Your partner has 50% more health - 340 points
Infinite ammunition - 480 points